> they could have phased out the gas guzzlers long ago

They have, gas guzzlers are taxed in the U.K. and the car industry is on notice that new petrol cars are banned from 2035 onwards. As a result the U.K. car market has shifted to offer many small efficient city car options.

> and developed decent mass transit.

We are talking about London, U.K. here. It’s literally had highly developed mass transit since at least the Victorian age.