Amtrak manages ticket prices for maximum profit (minimum loss) and has done so since Graham Claytor was President at least. This will only change if someone (Congress, state, etc.) starts providing large direct subsidies to Amtrak specifically for the purpose of reducing ticket prices.
I guess someone at Amtrak thinks that the Auto Train seats will keep on selling at the higher prices.
They're probably right.
Almost all the trains in the system have been getting large ticket price increases for several years.
There are relatively few routes where Amtrak seems to have perhaps hit the "price wall" where higher prices lead to lower revenue, and these routes don't include the Auto Train. On most of the routes, the seats seem to keep filling up even at higher prices, so it makes sense for Amtrak to keep raising the prices.
These were the only trains with dropping revenue from 2012 to 2013:
- Silver Star
- Silver Meteor
- Crescent
- Ethan Allen
- Niagara Falls / Maple Leaf
- Heartland Flyer
- Cascades
- Capitol Corridor
- Pere Marquette
These trains are the only trains where I would *not* expect Amtrak to be aggressively increasing prices; on these trains, dropping prices might make more money. (In some cases, this might be appropriate only temporarily; the Silver Star, Silver Meteor, and Cascades were all less attractive in 2013 due to disruptions, and as soon as the disruptions end I might expect the ticket prices to start creeping up again.)
Amtrak will increase prices until doing so stops making money.