The other day I wanted to change an airline ticket. I was told it would cost $250, plus whatever fare increase the new ticket would bring. So I skipped it.
Later that day, when I checked in online, I was informed the same flight was oversold and was asked whether I might switch to another flight and for how much. The options went as high as $500 in free travel.
So, let's see. If I wanted to change it myself, I got socked with made-up fees. But if they wanted to take it, they would pay me.
This makes as much sense as anything in the increasing greed of the airline industry, which borders on the obscene. Remember that Monty Python movie where the obese man just keeps...