When I was taking a statistics class in grad school one of the examples that was used in class was how movie theaters (at least in the 80s) did not give a discount on bundled food & drink offerings. People assumed that if popcorn, candy, and a drink were offered for $10 than that must be cheaper than buying them separately. And it worked pretty well - the bundles were sold at a high rate. But, if you checked the prices, you would see that the bundled price was simply the full price of each of the individual items. So, what else do these clever theaters do? Let's take a look based on some research I did (Google is your friend).
1. Advertising: Theaters have greatly increased the amount of local & national ads that they run before the previews. Research shows that movie goers don't seem to mind.
2. It smells so good in here: Chemicals are sometimes added to popcorn to enhance the aroma to make it smell stronger in the lobby and where you buy concessions.
3. Discourage early viewing: Theaters pay royalties on a movie based on when it is shown. They pay more per ticket on opening day, opening week, etc. Once the film has run for a week or two the theaters get to keep more of the ticket price. The longer you wait to see this month's blockbuster, the more their profit.
4. Sneaking in: They know you do it but they really, generally, don't feel it's worth the ruckus to kick you out.
5. Digital screenings: Digital is not Imax but many folks confuse the two. The extra money that a theater might charge for a digital screening is way more than their usually ticket price - it's very profitable for them.
6. Cell phones: They don't crack down too hard on cell phone disruptions because they do not want to discourage younger viewers (often their best customers) from returning.
7. Volume: The audio volume at many movies is higher enough to cause hearing damage.
8. Food: Some folks that work at theaters say that they would not eat the hot dogs, pretzels, and other prepared hot food but the popcorn and candy is okay. They don't elaborate but I think you can guess what might be the problem with those other offerings.
9. Small?: Most theaters have recently made their small popcorn the medium size as people buy the small too often. You are still getting a medium and paying the price for a medium. You still get a medium and that is more money for the theater and you think you bought a small which is better for your diet.
10. Cups: They really can't you an empty cup for sharing because they actually count the cups at the end of the evening to make sure that they are not given away. Sharing costs the theater a potential sale.
11. Cleaning up: No, they can't always clean up after every screening as there is often not enough time.
12. Starting time: Movies start late but end on time. They make you come early to view the ads. If they gave you the real starting time you might come then and miss the ads.
13. Fresh popcorn?: Not always. Popcorn keeps fresh enough to use the next day and can be warmed up. You might want to buy your popcorn a little into the movie if you are at the first showing of the day.
To be fair, not all theaters do all of these things but they have to do some or most of them to make a profit as most of the ticket money goes to the studios.