The New York Times tells us that if you focus only on trains and planes, Amtrak's share of the Northeast Corridor travel market is about half. The Washington Post tells us that it's one of the few sectors where Amtrak brings in more in fares than it spends on operating costs. If you've priced travel options in the corridor, you know that this farebox recovery comes from high fares.
In a post on Greater Greater Washington, Malcolm Kenton of the National Association of Railroad Passengers explains why Amtrak needs to charge higher prices, but he doesn't explain how they can. You might have wondered how a publicly owned company can afford, politically, to charge market prices. In other markets, transit operators face pressure from activists and politicians to keep fares low. Why haven't Northeast Corridor politicians raised an outcry about Acela Regional tickets?
Believe it or not, Randal O'Toole has your answer: it comes from other players in the market. Like a stopped clock that's right twice a day, O'Toole comes out with a useful insight once or twice a year, buried in his usual heap of misinformation. In this case, responding to the Times article, he's absolutely correct that the Northeast Corridor intercity market contains buses and private cars in addition to trains and planes. It also contains commuter railroads, which provide slower connections between city pairs like Boston-Providence, Philadelphia-Wilmington and Baltimore-Washington. New Jersey Transit and SEPTA even coordinate to provide cheaper service from New York to Philadelphia.
O'Toole dug up this chart that Amtrak themselves compiled (PDF, page 4) from unspecified data. It tells us that Amtrak carried only 6% of trips on the Northeast Corridor, and that airplanes carried 5%. The remainder is 89%, and O'Toole estimates that bus ridership is 8-9%. As far as I can tell he pulled that figure out of his ass, but it's all we've got to go on.
From all the market surveys, we know who's riding the bus in the Northeast Corridor: the poor and students. The buses have captured the low end of the market. Amtrak could have tried to fight them for it, but they could only have gotten prices that low by using their congressional subsidies on the Northeast Corridor instead of other routes. They would have lost money on all those low-end passengers, but not made it up in volume.
The buses, on the other hand, can make a profit at lower prices because most of their infrastructure costs (for roads and many of their terminals) are borne by the government. So they can serve the poorer passengers. Everyone makes a profit, and everyone can afford to travel! Nobody complains to their representatives about high Amtrak fares, because they can take the bus.
That, of course, raises the question: will the new burdensome law restricting low-cost bus lines in New York City drive up bus fares?