Dune 2 is almost 3 hours long. Why shouldn’t it cost more than a 90 minute romcom?

You're suggesting we should pay by the minute? I think I'll just keep not going to movie theaters.

if a theater can show a movie half as many times as usual it would make sense to rise prices.

At the limit if a movie came out to be 12 hours long then it would objectively cost the theater more to show (both in opportunity cost and direct costs)

I'm told that theaters make their money on food. As long as people are there eating popcorn and drinking soda they profit so it doesn't matter who those people are or what they are seeing. It's not as if theaters pay more for heat, water, and air conditioning if it's the same asses in seats vs new ones.

On other hand you could theoretically fit double the number of people if not more in 1 hour film vs 3 hour film.. And they likely would buy almost same amount of drinks and popcorn.