I've always been a proponent of that, but I want to be fair to the counter argument because its a fair one.
I agree on the sellout theory, especially with a place with really high-priced concessions in a Megalopolis market. At $11 a beer, you can make up that ticket difference a lot easier than at a school that doesn't sell beer at all. Sure, someone gets in for $15- then they spend $11 on beer, $6 on a burger, $25 on a hat...but then you have to also factor in the outlay for concessions with increased product moving...