The car argument is relevant because OK, you take a train from NYC to Seattle or some shit. It goes across thousands of miles. If you were to stop at a station to visit a relative along the way, you could get off the train and still be 3-5+ hours by car travel to that relative who lives in podunkville population 100.

We have an enormous amount of land that has very, very low population density. There are huge swathes that also practically have no to minimal population living there permanently.

Then we have places like Alaska that have absolutely insane supply chain (and thus costs for basic sundries) that really are only servicable by boat, plane or car unless you're building a stretch of rail through canada.

Much of the nation doesn't want to fund infrastructure for "city folk" and that's just around half of the people who vote on a nationwide scale. Even with some of the super liberal areas with tons of uber left leaning wealthy people, the left leaning wealthy people still push back on policies that require changing zoning from single family (wealthy) houses to high density housing despite being on commuter rail lines. Same towns complain that education costs are way too high and that they don't want to pay taxes for them because they just send their kids to private school anyway.

Wealthy NIMBYs rule policy for public transit, and the republican party also basically follows the philosophy of "fuck you, i've got mine" so although the technical solution is mass implementation of public transit, the problem is wealthy assholes controlling the media and politics, stopping any kind of major project from ever getting off the ground.