The barrier of entry for making movies is very low: with a few hundred bucks you have a camera and software to edit your video. If you want to make a movie about a couple of convenience store clerks, you just need a few friends as actors and an empty convenience store. Nothing too hard to get a hold of. You can reuse a lot of the real world to make an indie movie.
You can’t reuse the real world at all when making an indie game. If you want to create a game about a couple of convenience store clerks, you need to model the store and the clerks, then code all the behaviors in. That’s a lot of work. That’s the problem indie games face: they must create everything that’s in their game. That’s why games with abstract graphics (Geometry Wars, N, Rez) are so popular with the indie crowd: abstract graphics graphics are easier to make.