[majormajor]

You still end up with a ton of commuting needs. And you get an induced demand loop with development still: lots of jobs popped up in this area around the transit stops! Now more housing is built so people can live closer to it! Now even more commercial and retail is needed and gets built! Which makes even more people want to work/live there. And not all of those people are gonna want to both work and live there (consider the trivial case, even, of a couple with one job per person, with the jobs in different parts of town), so you've also increased your commuting demand, which means fuller trains, longer waits...

I've had coworkers who lived and worked in Beijing without cars - they still had 40+ minute each direction commutes. And that's a city that was extremely aggressive in expanding its transit. It's just a basic queuing/graph problem, though.

[marssaxman]

These all sound like good problems to have, relative to the current car-commuting sprawl mess, with its attendant CO2 and land use impacts.

[majormajor]

But hard problems to convince people to want who are used to air conditioned private pods instead of hot cattlecars with groping and harrasment, if we're just picking the least attractive elements of each method. "An hour, but on your feet crammed like sardines with everyone else" will get even less appealing to someone used to the car-based life if self-driving cars ever take off.

If people only make cases for transit by straw-manning the worst part of cars and ignoring the worst part of mass transit it's gonna take a long time to convince enough people to spend the billions needed to make it happen, since most people aren't stupid and they know that there are cons of public transit too, not just unalloyed pros.