Britain's King Charles arrives at the Luton DART central terminal at Luton Airport during a visit to learn about the new cable-drawn mass passenger transit system which will connect Luton Airport Parkway rail station to London Luton Airport, in Luton, Britain December 6, 2022. Yui Mok/Pool via REUTERS 

Britain's King Charles arrives at the Luton DART central terminal at Luton Airport during a visit to learn about the new cable-drawn mass passenger transit system which will connect Luton Airport Parkway rail station to London Luton Airport, in Luton, Britain December 6, 2022. Yui Mok/Pool via REUTERS 

Britain's King Charles meets airport staff during a visit to Luton Airport to learn about the new cable-drawn mass passenger transit system which will connect Luton Airport Parkway rail station to London Luton Airport, in Luton, Britain December 6, 2022. Yui Mok/Pool via REUTERS 

Britain's King Charles travels in a DART carriage for the three-minute journey to the Luton DART central terminal, during a visit to Luton DART Parkway Station to learn about the new cable-drawn mass passenger transit system which will connect Luton Airport Parkway rail station to London Luton Airport, in Luton, Britain December 6, 2022. Yui Mok/Pool via REUTERS 

Britain's King Charles meets a group of apprentices who worked on the DART, many of whom have now transitioned to permanent employment, during a visit to Luton DART Parkway Station to learn about the new cable-drawn mass passenger transit system which will connect Luton Airport Parkway rail station to London Luton Airport, in Luton, Britain December 6, 2022. Yui Mok/Pool via REUTERS 

Britain's King Charles meets staff during a visit to Luton Airport to learn about the new cable-drawn mass passenger transit system which will connect Luton Airport Parkway rail station to London Luton Airport, in Luton, Britain December 6, 2022. Yui Mok/Pool via REUTERS 

Britain's King Charles meets staff during a visit to Luton Airport to learn about the new cable-drawn mass passenger transit system which will connect Luton Airport Parkway rail station to London Luton Airport, in Luton, Britain December 6, 2022. Yui Mok/Pool via REUTERS 

Britain's King Charles travels in a DART carriage for the three-minute journey to the Luton DART central terminal, during a visit to Luton DART Parkway Station to learn about the new cable-drawn mass passenger transit system which will connect Luton Airport Parkway rail station to London Luton Airport, in Luton, Britain December 6, 2022. Yui Mok/Pool via REUTERS 

Britain's King Charles travels in a DART carriage for the three-minute journey to the Luton DART central terminal, during a visit to Luton DART Parkway Station to learn about the new cable-drawn mass passenger transit system which will connect Luton Airport Parkway rail station to London Luton Airport, in Luton, Britain December 6, 2022. Yui Mok/Pool via REUTERS 

Britain's King Charles travels in a DART carriage for the three-minute journey to the Luton DART central terminal, during a visit to Luton DART Parkway Station to learn about the new cable-drawn mass passenger transit system which will connect Luton Airport Parkway rail station to London Luton Airport, in Luton, Britain December 6, 2022. Yui Mok/Pool via REUTERS 

Britain's King Charles travels in a DART carriage for the three-minute journey to the Luton DART central terminal, during a visit to Luton DART Parkway Station to learn about the new cable-drawn mass passenger transit system which will connect Luton Airport Parkway rail station to London Luton Airport, in Luton, Britain December 6, 2022. Yui Mok/Pool via REUTERS 

Britain's King Charles travels in a DART carriage for the three-minute journey to the Luton DART central terminal, during a visit to Luton DART Parkway Station to learn about the new cable-drawn mass passenger transit system which will connect Luton Airport Parkway rail station to London Luton Airport in Luton, Britain December 6, 2022. Yui Mok/Pool via REUTERS 

Britain's King Charles III meets a performer in costume from the UK Centre For Carnival Arts during a visit to Luton DART Parkway Station to learn about the new cable-drawn mass passenger transit system which will connect Luton Airport Parkway rail station to London Luton Airport, in Luton, Britain December 6, 2022. Yui Mok/Pool via REUTERS 

Britain's King Charles III meets a performer in costume from the UK Centre For Carnival Arts during a visit to Luton DART Parkway Station to learn about the new cable-drawn mass passenger transit system which will connect Luton Airport Parkway rail station to London Luton Airport, in Luton, Britain December 6, 2022. Yui Mok/Pool via REUTERS 

Britain's King Charles meets a group of apprentices who worked on the DART, many of whom have now transitioned to permanent employment, during a visit to Luton DART Parkway Station to learn about the new cable-drawn mass passenger transit system which will connect Luton Airport Parkway rail station to London Luton Airport, in Luton Britain December 6, 2022. Yui Mok/Pool via REUTERS 

Britain's King Charles meets a group of apprentices who worked on the DART, many of whom have now transitioned to permanent employment, during a visit to Luton DART Parkway Station to learn about the new cable-drawn mass passenger transit system which will connect Luton Airport Parkway rail station to London Luton Airport, in Luton Britain December 6, 2022. Yui Mok/Pool via REUTERS 

Britain's King Charles meets staff during a visit to Luton DART Parkway Station to learn about the new cable-drawn mass passenger transit system which will connect Luton Airport Parkway rail station to London Luton Airport, in Luton Britain December 6, 2022. Yui Mok/Pool via REUTERS 

Britain's King Charles is shown the control room to learn about the new cable-drawn mass passenger transit system which will connect Luton Airport Parkway rail station to London Luton Airport, during a visit to Luton DART Parkway Station, in Luton Britain December 6, 2022. Yui Mok/Pool via REUTERS 

Britain's King Charles meets staff during a visit to Luton Airport to learn about the new cable-drawn mass passenger transit system which will connect Luton Airport Parkway rail station to London Luton Airport, in Luton, Britain December 6, 2022. Yui Mok/Pool via REUTERS 

Britain's King Charles unveils a plaque during a visit to Luton Airport to learn about the new cable-drawn mass passenger transit system which will connect Luton Airport Parkway rail station to London Luton Airport, in Luton, Britain December 6, 2022. Yui Mok/Pool via REUTERS 

Britain's King Charles unveils a plaque during a visit to Luton Airport to learn about the new cable-drawn mass passenger transit system which will connect Luton Airport Parkway rail station to London Luton Airport, in Luton, Britain December 6, 2022. Yui Mok/Pool via REUTERS 

King Charles III unveils a plaque during a visit to Luton Airport to learn about the new cable-drawn mass passenger transit system which will connect Luton Airport Parkway rail station to London Luton Airport, in Luton, Britain December 6, 2022. Yui Mok/Pool via REUTERS 

Britain's King Charles III is shown the control room to learn about the new cable-drawn mass passenger transit system which will connect Luton Airport Parkway rail station to London Luton Airport, during a visit to Luton DART Parkway Station, Britain December 6, 2022. Yui Mok/Pool via REUTERS 

An electric mass transit bus assembled by electric vehicle manufacturer Roam is seen at the Green Park Terminus in Nairobi, Kenya October 19, 2022. REUTERS/Monicah Mwangi 

A police officer walks next to an electric mass transit bus assembled by electric vehicle manufacturer Roam at the Green Park Terminus in Nairobi, Kenya October 19, 2022. REUTERS/Monicah Mwangi 

A construction worker stands near an underground MRT (Mass rapid transit system) tunnel in Jakarta, Indonesia, September 20, 2022. REUTERS/Ajeng Dinar Ulfiana 

A construction worker stands near an underground MRT (Mass rapid transit system) tunnel in Jakarta, Indonesia, September 20, 2022. REUTERS/Ajeng Dinar Ulfiana 

A woman wearing a face mask walks out from a Mass Rapid Transit (MRT) station amid the coronavirus disease (COVID-19) outbreak in Kuala Lumpur, Malaysia, February 25, 2022. REUTERS/Hasnoor Hussain 

A crypto exchange advertisement shows a Bitcoin symbol at Mass Transit Railway (MTR) station, in Hong Kong, China. October 27, 2021. REUTERS/Tyrone Siu 

A crypto exchange advertisement is seen at Mass Transit Railway (MTR) station, in Hong Kong, China. October 27, 2021. REUTERS/Tyrone Siu 

A crypto exchange advertisement shows a Bitcoin symbol at Mass Transit Railway (MTR) station, in Hong Kong, China. October 27, 2021. REUTERS/Tyrone Siu 

An advertisement for crypto exchange shows a Bitcoin symbol at Mass Transit Railway (MTR) station, in Hong Kong, China. October 27, 2021. REUTERS/Tyrone Siu 

Advertisements for crypto exchange show a Bitcoin symbol at Mass Transit Railway (MTR) station, in Hong Kong, China. October 27, 2021. REUTERS/Tyrone Siu 

Passengers wearing protective masks walk through the Central Mass Transit Railway (MTR) station in Hong Kong, China August 17, 2021. Picture taken August 17, 2021. REUTERS/Tyrone Siu 

Security stands guard during mass vaccination program for the coronavirus disease (COVID-19) at a Mass Rapid Transit (MRT) station, as cases surge in Jakarta, Indonesia, July 23, 2021. REUTERS/Ajeng Dinar Ulfiana 

A student reacts as he receives a dose of the vaccine against the coronavirus disease (COVID-19) during a mass vaccination program at a Mass Rapid Transit (MRT) station, as cases surge in Jakarta, Indonesia, July 23, 2021. REUTERS/Ajeng Dinar Ulfiana 

A student reacts as he receives a dose of the vaccine against the coronavirus disease (COVID-19) during a mass vaccination program at a Mass Rapid Transit (MRT) station, as cases surge in Jakarta, Indonesia, July 23, 2021. REUTERS/Ajeng Dinar Ulfiana 

A healthcare worker in personal protective equipment (PPE) checks a man's temperature with a thermal scanner before he receives a dose of the vaccine against the coronavirus disease (COVID-19) at a Mass Rapid Transit (MRT) station, as cases surge in Jakarta, Indonesia, July 23, 2021. REUTERS/Ajeng Dinar Ulfiana 

People wearing protective face masks wait to receive a dose of the coronavirus disease (COVID-19) vaccine during the mass vaccination program at a Mass Rapid Transit (MRT) station, as cases surge in Jakarta, Indonesia, July 23, 2021. REUTERS/Ajeng Dinar Ulfiana 

A view of Mass Rapid Transit train during a lockdown due to the coronavirus disease (COVID-19) outbreak, in Kuala Lumpur, Malaysia June 1, 2021. REUTERS/Lim Huey Teng 

A worker walks at the construction site of the Mass Rapid Transit (MRT) system station in Jakarta, Indonesia, May 31, 2021. REUTERS/Ajeng Dinar Ulfiana 

Workers construct the new Mass Rapid Transit (MRT) system receiving substation in Jakarta, Indonesia, May 31, 2021. REUTERS/Ajeng Dinar Ulfiana 

A worker constructs the new Mass Rapid Transit (MRT) system receiving substation in Jakarta, Indonesia, May 31, 2021. REUTERS/Ajeng Dinar Ulfiana 

Workers construct the new Mass Rapid Transit (MRT) system station shaft in Jakarta, Indonesia, May 31, 2021. REUTERS/Ajeng Dinar Ulfiana 

A child poses for photo at a model of a Mass Transit Railway (MTR) station during an open day to mark National Security Education Day, at Hong Kong Police College, in Hong Kong, China, April 15, 2021. REUTERS/Tyrone Siu 

Children play behind a member of the Railway Response Team at a model of a Mass Transit Railway (MTR) station during an open day to mark National Security Education Day, at Hong Kong Police College, in Hong Kong, China, April 15, 2021. REUTERS/Tyrone Siu 

Children play with toy guns next to a member of the Railway Response Team at a model of a Mass Transit Railway (MTR) station during an open day to mark National Security Education Day, at Hong Kong Police College, in Hong Kong, China April 15, 2021. REUTERS/Tyrone Siu 

A child walks past a member of Railway Response Team at a model Mass Transit Railway (MTR) station during an open day to mark the National Security Education Day, at Hong Kong Police College, in Hong Kong, China April 15, 2021. REUTERS/Tyrone Siu 

A child plays with a mock submachine gun at a model Mass Transit Railway (MTR) station during the open day to mark the National Security Education Day, at Hong Kong Police College, in Hong Kong, China April 15, 2021. REUTERS/Tyrone Siu 

People wearing protective masks and following social distancing measures ride a Mass Rapid Transit train, amid the coronavirus disease (COVID-19) outbreak in Kuala Lumpur, Malaysia October 30, 2020. REUTERS/Lim Huey Teng 

A woman wearing protective mask passes by a mural at a Mass Rapid Transit station, following the outbreak of the coronavirus in Kuala Lumpur, Malaysia, March 3, 2020. REUTERS/Lim Huey Teng 

A worker sweeps dry leaves in front of a Mass Rapid Transit (MRT) station, temporarily closed to prevent the spread of the coronavirus disease (COVID-19) in Jakarta, Indonesia, April 28, 2020. REUTERS/Ajeng Dinar Ulfiana 

A man who is living in the New York subway system sleeps in a relatively empty station as the outbreak of the coronavirus continues in the subways of New York, U.S., April 13, 2020. Picture taken April 13, 2020. REUTERS/Lucas Jackson To match Special Report HEALTH-CORONAVIRUS/NEWYORK-HOMELESS 

Social distancing markings are seen at Westminster tube station, amid the coronavirus disease (COVID-19) outbreak, in London, Britain April 21, 2020. REUTERS/Hannah McKay 

A social distancing marking is seen at Westminster tube station, amid the coronavirus disease (COVID-19) outbreak, in London, Britain April 21, 2020. REUTERS/Hannah McKay 

Notices are seen on a London bus indicating to board at the middle doors, as the spread of the coronavirus disease (COVID-19) continues, London, Britain, April 19, 2020. REUTERS/John Sibley 

Subway seats are marked for social distancing during the coronavirus disease (COVID-19) restrictions in Toronto, Ontario, Canada April 18, 2020. REUTERS/Chris Helgren 

A bench is seen at a empty Hua Lamphong train station in Songkran holiday which marks the Thai New Year during the coronavirus disease outbreak (COVID-19) in Bangkok, Thailand, April 14, 2020. REUTERS/Jorge Silva 

Empty seats are pictured at Hua Lamphong train station in Songkran holiday which marks the Thai New Year during the coronavirus disease outbreak (COVID-19) in Bangkok, Thailand, April 14, 2020. REUTERS/Jorge Silva