Trains manage to do that in most countries, given a few minutes walk to and from a station.
I don't commute now but I used to commute two hours in the UK, and I walked 3 minutes to a train station, and then took a couple of trains all the way, and then a 3 minute walk at the other end to my office. And I lived in a small village not a major area.
Why can't they do it in the US?
Take just the Northern California region, then, around the same size as the UK. Now there's no argument about size difference. The population is around a third of the UK, so while that's less and so lower density, it isn't a crazy difference and the major areas of population themselves where you need the stations are high density.
I can go from any city in the UK, to any other city in the UK, via a couple of trains pretty effortlessly. Why couldn't that be replicated in an area of the same size and more of less the same population, in California?
Why can't it be replicated just in the Bay Area even! Why aren't there lots of trains there?!
1.) The Bay Area is made up of 100 cities and towns and several counties. There is not a single “Bay Area government.” Every single transit project has to be approved by several levels of government and funded by the state and federal government. Moreover, that funding and consent has to last for decades to keep the project on track. It rarely does. Every train line in the Bay Area was the result of a fight.
2.) Trains require density to be feasible. Density increases the supply of housing, driving down the value of existing single family homes. Owners of single family homes store a significant amount of their net worth in the equity of those homes. Municipalities rely on the property taxes from those high value homes.
3.) The Bay Area is not zoned for density. Trains will not catch on here because 60 odd years ago the people who designed the highway system did not consider the possibility that many people would need to live close together to make the place affordable. No one was thinking of affordable housing then.
But the density of even the wider Bay Area region (the CSA) is higher than the entire UK! How come that's dense enough for lots of trains in the UK but not dense enough for trains around the Bay Area?