I never said that start-ups weren't hiring high school students. I said that they were less likely to hire than big companies.
Big and medium sized companies have internships for high school students too. They are the ones who can afford to train workers while most start-ups need people who are ready to create a product right away before their funding dries up.
I don't think I've ever heard of a big company having a programming internship for high school students. They have internships in other fields, but to my knowledge, programming ones are rare to nonexistent.
Correct me if I was just ignorant to them, though.
Obviously the number of these internships is limited. But that is also my point: a high school student (not you necessarily) is rarely suitable for creating commercial products until many months or even years of training. That is why people hire college graduates.
Big and medium sized companies have internships for high school students too. They are the ones who can afford to train workers while most start-ups need people who are ready to create a product right away before their funding dries up.