With a good planning and a little time (unfortunately slightly in the decades) you can build infrastructure to be around the train network. Make sure you have a good connection from home location to a hub and infrastructure development around the hub for shops and offices as well as train lines to factories for factory workers as in Tokyo, combined with an integrated schedule as inspired by Switzerland and you get quite an attractive urban experience. But yes, that is a major shift from America's car focussed infrastructure.

In the US, 200 years is a long time, and the train doesn't go where you're going. In Europe, 200 km is a long distance, and it might.

In Singapore, 50 years is a long time and the train goes where you're going.

I'm not saying the US could pull off a Singapore, but there's no excuse for San Francisco, or LA, or any other large city to have done so.

We have highways everywhere... We could definitely dedicate the left most lane and convert every left most lane into people moving train tracks. Just because we haven't doesn't mean it isn't economical or feasible.