I mean one example in the US I can look to is a city I lived in for a bit, Seattle. They have been actively expanding their public transit and even when I lived there I didn't use a car to get around and honestly the only problems I had was trips taking a bit longer sometimes and busses running not on time both of which are problems that can be fixed and with the expansions are actively being fixed. If you want an end game for what public transit can look like Europe is a great example. While I don't think America can ever quite reach that level I think we could definitely reach a point where cars are still required but only for people living further out in the country. Heck if you want a good example for public transit in a larger country the high speed rail China has been building is pretty impressive. Don't know the most about it but I've heard fairly good things about it (of course ignoring the other problems with China, but that isn't related to public transit). Overall public transit does work and works well especially in the cities that actively invest in it like Seattle and Portland (both of which I've lived in/near). The problem in America with adoption just comes from a very car centric attitude which at least in the cities I mentioned before has been slowly getting better as people start to realize that public transit benefits everyone, including drivers. Just because we have to fight to show that it benefits everyone and that building bigger roads doesn't help doesn't mean we should just surrender to car infrastructure because it's hard and takes a long time to push for public transit investments.