Actors Contracts for Minors

As I understand it minors cannot be held to contracts unless it is something for their basic needs like housing, medical or food.

But I was reading a site about the old PBS show Zoom.

It said the kids on the Zoom show had to sign contracts agreeing NOT to appear in commercials or TV for the next three years after they left the show.

So how could this be enforced? Or could it?

Then I thought about actors in general. We have tons of kid actors and they have to have some sort of contracts. How can they be enforced?

Logical Wild Ass Guess (LWAG) Parents would also sign and be held to the contract.

So if the actor turned 18 (or was emancipated) he could just quit and his parents would be sued? :dubious: