We did have city trolleys that got run out, and there are places where bullet trains would make sense now, but it's really hard to fight the airline lobbies. I don't think of it as evil conspiracy, but just common sense for those interests to defend what they already control. In the late eighties there was a push to set up a nice triangle from Houston to Dallas to Austin/San Antonio, but Southwest Airlines really put up a fight (among others). It's taken forever for the Seattle area to get its trains going, despite having built a tunnel through downtown ages ago (has been used for buses and I think about a year and a half or so away from having light rail go through).
Now not many people going from OKC to SF, but the NE Corridor works and the Texas triangle and a run from Seattle to SF at high speed would probably work in the long run. Sprawling cities like LA, Houston and Dallas could sure use a BART or MARTA, but the initial cost and planning is high, and we're a now put it on Credit Card culture. Rent, don't buy. I think it was 3 times that voters in Seattle approved light rail / monorail plans and the light rail is still struggling to get going and is more long distance than within the city. (BTW, they voted against stadiums as many times and have nearly a billion dollars worth of stadiums anyway).
I think the emblematic US approach is MILW deciding it'd be better to tear down their electric to sell the copper instead of finishing the line out and then having costs under control in the long run. I remember having high hopes years ago that mag-lev or other high-speed would start out on the East Coast or in TX and spread out to form a new network, but there's just too much vested interest in keeping us in cars and on planes now. A lot of near broke big businesses with some to spend defending their feif, and not a lot of rich dreamers with long term goals like a Gould et al. Scratch out the trains in planes trains and automobiles for most American passengers for our lifetimes.
Imagine if SWA had decided, hey, let's diversify and be an investor to get the return on these new trains....