As said many posts above, nobody is going to voluntarily reduce their standard of living. You will have to force them. How you do that will be one of the biggest political conversations of this century and not at all easy or simple.
First of all I'm saying this will not reduce anyone's standard of living. Give them a great transit system and they will use it until they realize the cars are mostly sitting around. Further I gave them an out: you keep one car (truck?) for the times when they are better.
Now I will agree that some people will not give up their cars. However I think the majority will if you just give them a better option, and this is the first win that we need to chase in most of the US. More importantly you have to do things this way. Start with forcing people and they will discover you reduced their standard of living and they respond by voting you out and undoing everything making transit worse. Start with making the system better and you can then win when people don't care since it mostly doesn't affect their life anyway.
Manhattan is one of the rare exceptions in the US where transit is good enough that you can apply a stick to the last hold outs driving when they could take transit - enough people already take transit that they won't care what you do to cars, and many of the remaining drivers really need a car (they are delivering something that can't go on transit) and they find paying for lower congestion makes their life better. Manhattan has a lot they need to do to make transit better there too, but at least they are good enough.
Public transport requires density to be cost effective. You can't have a "great transit system" everywhere in a large country. Not here in small and dense England, and not in Germany or Japan either from what I've seen.
The vast majority of land in almost all countries is rural where there isn't enough density. However most people do not live in those areas.
The whole point of this thread since my comment has been "will people do it" not "is it possible". We've had decades of notice and yet the very Democratic suburbs near me still have done nothing but put in a handful of bike paths and patted themselves on the back.
Of course it is possible to do things differently, but very many choose not to do so. This is all in justification of my original point- that "corporate greed" in the parent post is a bogeymen when we can see the same decision process is made by many kinds of people.
The Republicans are at least honest about not caring about transit...