Which sucks if you're an adult making a living who happens to be young, but that's what we do.
There's also a dirty hack: We call some young people "apprentices"(1), which sometimes means the same job as before and not having to pay the minimum wage, with a veneer of marketing. See also "unpaid interns".
(1) I don't want to disparage proper apprenticeships, which from reports can be excellent, e.g. at engineering firms like Rolls-Royce.
by the way, we do have special rules in the US for what kind of work you are allowed to give to interns. in general you are not allowed to give work to interns that would otherwise be performed by a full employee. this is intended to prevent adult employees being put out of a job by low pay interns. unfortunately, I don't think most minimum wage employers are interested in dealing with these complicated rules for interns.
when you put it like this, it seems obvious to say that the right move is to screw over the teenagers who are much less likely to be supporting a family or themselves.
I'm not sure this is great in the long run though. imo, having some kind of part time job is very important in highschool. for a lot of teens, it might be the first time they are exposed to an environment that has no inherent reason to make things work for them. until we finally get luxury space communism, this is a really important experience to have early in life.