So what's your proposal? Go back in time 200 years and create a public-transit system?
The US is huge. There is no feasible way to support public transit for 95%+ of it's land-mass. That's not going to change anytime soon, or ever.
Also, most mass-transit systems in the US operate at significant loss, even with government (ie. taxpayer) funding and collecting rider-fare. A lot of public transit systems are in complete disrepair and are severely lacking. Buses and lightrails are never going to be "cheaper", as convenient or accessible as roads and vehicles are.
What I would do is the same as what most cities around the world are doing, spending more on public transport, spending less on roads, implementing tolls and congestion charges, and over time reshaping cities to be better for walking, PT, and cycling.
The US is not unique in having fully adopted cars and ripped up old PT networks. It happened all over Australia which is also a massive very spread out country. But significant effort has gone in to reversing the damage.
There is something deeply wrong about a society that can afford to create hundred billionaires but can’t afford busses.
Who cares about 95% of its landmass? You build things where people are, not uniformly across the surface.
I subscribe to the opinion that there are probably some good reasons why people in the US tend to spread out when they have the option. I think the problem of collective human action is complex enough that optimizing at the individual level is probably the best we can do. I would rather spend time thinking about how to serve people in ways that they actually want instead of “big idea” approaches.
Infeasible?
Perhaps it is indeed infeasible today because of differences in economics and regulation, but: We already created it once -- for huge areas.
As evidence supporting the notion of this prior existence, I'd like to introduce this 1908 map entitled Electric Railway Map of Ohio, Indiana, and Michigan: https://curtiswrightmaps.com/product/electric-railway-map-of...
(Those lines were real, and they were also generally privately-funded.)