The main problem with the US interstate train system is that it's run on freight train lines. Amtrak and Acela do not actually own the railway they use and they can only go a certain speed due to the grade of the track.

I don't think you would be willing to pay the amount of taxes you would need to, to completely redo the railways haha.

Anyways Amtrak are barely turning a profit as it is and while it would be great to have Euro quality train lines, the economics aren't there. Even in Europe they're having a hard time competing with flixbus.