When I was a kid in the 90's, I could see a movie for $1.50 in the evenings or $1 for a matinee ... in the midwest. They weren't first run movies, but rather movies that were in between their time in the movies and when they went to video. I'm guessing a few of them might have been on HBO during that time frame, but it really didn't matter.
Some years later, that theater quit doing the second run movies and switched to regular movies. I feel kind of lucky that it was after I moved away and had basically quit going to theaters anyway.
I'd probably go more often if things were of similar cheapness. The low cost also meant that I'd be more willing to see comedies and take chances on other movies that don't truly benefit from a large screen and sound system. I also wasn't all that out of sorts if the movie wasn't very good since even at that time, it wasn't much money.
I truly think the advantage of movies in the 70's and early 80's was the lack of popular home video. If you didn't see the movie, you missed out. And I think that helped afford somewhat higher prices, though they didn't need to charge less for second showings as they used to do (Disney cartoons, for example).