system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do actors/actresses in their late 20s and their 30s play high school kids in movies?

I've never understood why they cast people who are way older than teenagers to play high school students in films.
gpt
Because dealing with actual kids is a lot harder than simply pretending that the adult actors are kids.

In addition to the lack of experience that come with younger age you will also have to deal with all sorts of regulations intended to protect children from exploitation.

Finally there is in some cases the problem that children tend to grow up. A 15 year old kid can change their appearance dramatically over a few years while a twenty something will have much more consistent looks.