>A big problem is that it often isn't a free market. Joe The Sandwich Guy can't just randomly decide to open up a store inside the airport. There's a limited amount of space, a lease can easily last a decade, and any that come up are usually granted rather than auctioned.

It's basically like a professional license. The system is designed to make you waste so much of your life and money entering the market that undercutting people by any appreciable amount is the last thing you'll do once you're there.