They've also got a captive audience, almost none of whom are going to go out of the airport to go to a competitor because they'd have to suffer through the traf

They've also got a captive audience, almost none of whom are going to go out of the airport to go to a competitor because they'd have to suffer through the traffic, parking, and security lines to get back in. It's a similar thing with ski resorts, skating rinks, bowling alleys, etc.. all of whom tend to charge exorbitant prices for mediocre food, or worse.