While i kinda agree with you, it doesn't fly for most US cities.
Most US cities aren't dense at all. A lot of them were built with transportation in mind. London and European cities in general are so much older that their city centers have no real way to accommodate that.
So what do you do? You provide non car options. Technically they exist in US cities too, but especially on the west coast they're just not a viable alternative. Nobody who can choose will take a 2 hour public transit trip over a 20 minute drive. Heck, in a lot of cases biking might be faster than your transit option, albeit riskier
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.
West coast cities like Portland and Seattle both have very good transit and in my experience is generally better than driving since traffic and parking are awful. Where I live on the west coast is a mid sized city and transit is completely viable, my family only drives on weekends for example.
> West coast cities like Portland and Seattle both have very good transit
I live in Portland. Traffic is often quite slow. And even then it is much faster than public transit unless your destination is just a few miles away and on the same line.