Because you make your profit on the "margins":

http://qz.com/533501/half-of-america...its-customers/

No, GTL, you make your profit from high-value customers. Most businesses understand that. It's one of the reasons guys who spend nothing in Vegas, get nothing. And the high rollers. . .

Revenue based made sense from the point of view of the airlines. A good analyst of the airline industry would have intuited that a long time ago. GTL, however, knows this rains on his business. But it doesn't on AA's or any of the other airlines.