After doing some research, I have to correct my earlier post...Amtrak will make plenty on it, if they sell it from Champaign onward. The accommodation charge from Chicago to Champaign is probably the same as to a point much further down the line, so they may in effect be earning double for a portion of the way, if it does sell beyond Champaign.
I see that now Amtrak does charge more on the accommodation charge for each further station.
At one time, they charged the same amount for an Economy Bedroom (now Roomette), from Denver to Granby, as they did all the way to Shoshone. From the next stop, Boise, the room charge increased. So when going to Seattle, I took advantage of that by booking from Denver to Shoshone in the room (and getting the 3 included meals), and then moving into the coach to save money...