I have compared them, and I don’t see what you’re seeing.
Depending on how you measure (do you include European Russia, ie the bit west of the Urals?) Europe is larger.
Yeah, NYC to Chicago is about 18 hours over a continental divide. You do out west and things get even further. Outside the Northeast corridor and a few other city pairs, train trips are pretty long in the US.
I've been tempted to do at least part of one of the long distance US train routes but I think I'd get pretty bored, I'm guessing the food isn't very good, and I've spent a lot of time out West.
The US isn’t that much larger, I don’t think this argument holds. The geography and locations of population centres seem more of an issue.