As bad as the passenger rail situation is in the US, I can totally understand how it got this way compared to other countries from a pure geographic point of view.
The US landscape is ideal for freight trains and not quite as ideal for passenger trains.
If you look at countries like Japan, the geography makes a perfect condition for passenger trains to be most ideal. Railroad as a shipping method for goods doesn't make a lot of sense, you can just put goods on ships that travel along the coasts and for shorter journeys trucks make more sense.
Or look at China: massively higher population, and their population is much more concentrated in the East of the country than the US with its split up coastal populations. Maybe we could say that a high speed train between Indianapolis and Cleveland would be nice, but there isn't even a single direct commercial direct flight between those destinations, so how will anyone fill up a train? China's huge population makes it an extremely ideal high speed rail use case.
But in the US, putting goods on a train from Chicago to LA makes way more sense than any sort of truck or ship situation. And even a high speed train on that route wouldn't make a whole lot of sense compared to a flight.
But there's definitely room to improve geographical coverage in specific corridors where that expansion would have great positive impact.