[aperson_hello]

As you allude to, this is a massive zoning issue (especially in the US). The infrastructure required to move people from their houses to places of work and shopping is insane, given where all those houses and places of work and businesses are. To make trains viable for everyone, you have to rework the entire built environment to move all of those places into different locations so that people can get from one place to another efficiently.

I live in a small/midsize city with relatively ok public transit for its size and the only places I ever take it is to downtown or the airport - places where parking logistics are terrible and it's easy to get to on public transport. Anywhere else (like going to the store or work) and getting there takes hours without a car. Living in areas that have better connections or better walkability triples my housing cost, so I own a car and drive. Cities need to be significantly more dense for more trains to make sense, but that density means clearing out all of the less dense buildings and building new. That's extremely costly and doesn't actually help the environment because of the massive amount of carbon needed to fix that everywhere.