When I was a minor, I signed up for a Jack Lalanne membership. Two months later I decided to quit/ break the contract and because I hadn't had a parent cosign the agreement Jack Lalanne was unable to sue for losses.
So ... "it's not only not okay, but probably not legal."
Yes ... but the vast majority of American's can't home school because both parents are working. So the vast majority of children have to be sent to either a public or private school. And courts constantly rule that children in public school (or anyone on school property) have their Rights limited.