I suspect that if a metro would be built in a large car centric city over time the city would adapt to the metro and become less car centric. But making the economical argument for building the metro in the first place would be very hard. It would pay back over a time scale that capitalist economies hardly consider.

No, capitalist economies tax effort and spend it on longer-term things. It's democracies where things can be rolled back by the next leader that are the main cause of short-termism.

(I don't have a better alternative to democracy; just stating that's where the flaw is. Well, that and zero incentive to do things well/efficiently outside of political kudos).

Things used to work pretty well in capitalist democracies when the capitalists were well regulated and taxed and the demagogues didn’t have unrestricted personal access to the voter base.

That was a pretty brief period, wasn't it?