Most places where people want trains have them (high density places).
This doesn't address OP's comments. To remind you, they mentioned "cheap, easy, high speed travel across the country". I would grant Amtrak is easy. It's not the other things though...
Care to flesh this out?
I can only find data that contradicts this:
https://railpassengers.org/happening-now/news/releases/new-p...
https://media.amtrak.com/2023/08/data-finds-overwhelming-sup...
Most places where people want trains have them (high density places).
This doesn't address OP's comments. To remind you, they mentioned "cheap, easy, high speed travel across the country". I would grant Amtrak is easy. It's not the other things though...