In theory it would work well in the US as many major cities are spread roughly that distance from one another.
Kraków, Poland with 780k inhabitants has "only" 10
https://www.openstreetmap.org/#map=18/50.06881/19.94768&laye...
The fix is not easy. But building taj mahal type trains isn't helpful. (simplistic trains might be - using the lower cost to build more is useful). Those of you watching local politics need to scream "NO EXTRAS, only the cheap reliable system done fast" at all local meetings to counter those asking for beauty.