US is too big and too sparsely populated both on a large scale and small scale for trains like Europe, Japan and China.
There's a part where no one talk about, and that's the infrastructure within the city are not conducive to trains. People get to a train station and they need to get around and unless you're talking about New York they really just need another car.
This in comparison to European and Asian cities where your friend can just post you an address and you can use public transit all the way to the last block.