I don't want to scrap it all, just the parts that require hefty subsidies to serve places that have realistic alternatives. US households usually have cars and for those that don't, intercity buses tend to serve even very tiny burgs. So most people most do have realistic alternatives.

Trains are the right solution in some cases. Commuter rail often makes sense. And in some densely populated regions, intercity trains make sense too. But in most of the US, because of the distances between cities, cars and planes work better.