I do not think this is true. I think people have an easier time seeing themselves in an Acela car than they do in a Jetblue seat --- which is part of why the Acela is so popular. People don't drive from DC to NYC so they can signal their independence. Pretty much, they don't drive from DC to NYC at all.

Where HSR is feasible and built out in the US, it gets used. The problem is, HSR isn't feasible for the most economically important routes in the US.

You can get from London to Paris in 3 hours on a train, and from Paris to Frankfurt in about 5. Almost as a rule, the most economically central European cities are closer to each other by rail than the most important American cities are --- excepting the Eastern Seaboard, where we have rail --- by air.