IINM, Amtrak is a private company, but recieves annual funding from various levels of Government. The lower down the totem pole you go, the more generous elected officials are willing to be towards Amtrak.

Amtrak itself came about as a result of pretty much every railroad in the US withdrawing their passenger trains. Moving people was never profitable (or perhaps marginally so), even in the heyday of the passenger fleet. Rather, it was the extra revenue generated by the mail that allowed the vast numbers of passenger trains to flourish. As air and road took larger and larger pieces of the Mail traffic away, the trains became unprofitable.

In it's own way, Peak Oil will force mail back to the rails (as trucking and air companies go bust), and help with a rebirth of long-distance rail passenger travel. :)