I think the difference is -- the Interstate is heavily used, so it makes a good government subsidy (that is, you don't have a large number of people paying for

I think the difference is -- the Interstate is heavily used, so it makes a good government subsidy (that is, you don't have a large number of people paying for a very small number of users). But passenger trains would end up being the opposite -- large number of people paying, and a small number benefiting. Now you can have some routes (such as the Buffalo to NYC one that you mentioned), but again if it is paid for federally, then unless there are similar situations that the majority of the country could take advantage of, it doesn't make sense.