I think this is like flight pricing. People don't typically think about luggage fees, meal cost, wifi charges, etc. They only look at the flight price and wheth

I think this is like flight pricing. People don't typically think about luggage fees, meal cost, wifi charges, etc. They only look at the flight price and whether the flight time is convenient for them. This means airlines/theaters are free to charge a premium once you've purchased the main ticket. Also, the numbers involved here are pretty low. I don't know many people who would drive across town for a theater with cheaper popcorn, even if such a theater existed.