While there is obviously no one easy solution for every city situation could easily be improved in a lot of them if there was political will. At least it would be 1000% more sane than pitching underground car tunnels.

It obviously take decades not years, but again Tesla full self driving was promissed back in 2016 and something tells me it would be a big success if it will be deployed on scale in 2036.

People don't want to change. In the us on the west coast I would say that public transit has a bit of a stigma. You don't use it unless you have to.

Couldn't be more different in the big European cities, using a car there is (made) cumbersome.