Most of America lives in urban areas. Rural communities, where they exist, have no need to change. Running busses out there doesn’t make sense. What also doesn’t make sense is, for example, in Ohio the Ohio Department of Highways (ODOT) spending a billion dollars to “ease congestion” in downtown Columbus, Ohio so that folks can live further away and drive to work or whatever. It’s a tax subsidy that I don’t think we should pay, and it’s not a good use of money objectively either.
Second we don’t have to make this trade off you are imagining. I live in a European style (as close as you can probably get in America) neighborhood with shops and restaurants within walking distance. I also have a large garage (with only one car) and live in a single family home, and live alongside duplexes, triplexes, big houses, small houses, shops, and more. Today I can use my car as you’d expect. But what’s missing is the ability to not use my car to go to the grocery store and get a steak or something.
With respect to safety you can just avoid the problem by switching products. Walk, bike, rail and you don’t have to get in a car crash.
The trade-offs that folks think must exist simply do not exist. The trade-offs are do we spend an absorbent amount of money, have more people die, face insurance premiums that increase with no recourse, have to be upset at gas prices, &c.
Or do we just not do that?
Which is the difficulty in talking about "America needs to do such and such": we are much more diverse, and when we're talking about one context someone else hears their context or isn't able to imagine a different context. Perhaps these kind of conversations would be better had at local levels than national
Unfortunately transportation policy is heavily influenced at the national level and the federal government doles out gargantuan amounts of funding to keep the highway lobbying industry happy. We can't only have a local conversation or even a state conversation, though of course those conversations happen as well and are arguably more important.
I walk 10k steps a day on a normal day, only drive when necessary to go out of my normal routes. This has an added benefit of keeping me, an aging programmer, in shape (as well as other relevant activities).
Nothing dramatic about it at all.
They lose hours, lives, and a boatload of money every day in the current state. Removing the reliance on cars will improve those things.