To what extent should "public goods" be subsidized? What are the limits?
Transportation is taxpayer-subsidized or government-run in the US. Airports, roads and highways, and mass transit, for starters. All of these things were once entirely private ventures.
In the Boston to DC corridor, Amtrak is a wonderful thing and it is heavily used. It's quicker and cheaper than driving and parking, and it takes you from downtown to downtown instead of to a distant airport.
Whether Amtrak is overly-subsidized is another question, which I cannot answer. However, I would ask these folks who are mooning Amtrak in Calif. whether they would like their California interstates taken away. The NY Sun a while ago was not too keen on Amtrak subsidies, but when they discuss the far-cheaper cost of busses, they ignore the fact that the highways they use are government-built and maintained.
Photo: A high-speed Acela engine