But the problem with the passenger train in the US is: what do you do when you get there? You need the car that you left in the parking lot. Assuming the train station has one, and that you don't mind paying a parking fee bigger than the train fare.
So you hire a car? Quick - how many train stations have a rental counter, and how many have a parking lot big enough to hold the rental cars. And now you're paying a car rental fee that again is more than the train fare.
That's the issue: public transport has to be a continuous web, otherwise the incentive is gone. And intercity passenger rail is the last piece that should be built, after the intra-city buses, jitneys, light rail, whatever.
If you want to make a start on fixing the US's absurd transit system, start by getting freight off the roads.