system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are movies shot at 24 fps?

Especially when we have the technology to shoot them at 60 fps, which looks arguably better.
gpt
Early film was expensive, and not very sensitive. You needed a lot of light to enter the camera to get a good picture.

You can solve both of these problems by running at a low frame rate.

The lower the frame rate, the longer the shutter is open and the more light you can get into the camera. At the same time, low frame-rates mean you use less of that expensive film.

This is why the film industry settled on 24 fps. 24 fps is pretty much the slowest frame rate that the human eye interpenetrates as motion. If you go slower than 24, viewers start perceiving each frame as a separate still image instead of a moving image.

24 fps has very distinctive look and feel. Even though we have technology that allows for much higher frame rates, it changes the character of the image. A movie filmed at 60 fps doesn't look like a movie. The look of 24 fps is just so engraved in the minds of movie goers that anything else just looks wrong to them.