Kids will find a way to sneak around their parents every time, esp. if their friends (or a groomer) introduce them to something "cool". Active parental monitoring alone isn't really a solution.
Automated access control is even worse. Kids explore technology a lot more than their parents do. They will find a work around and share it among their peers. The only real solution is to make them aware of the dangers and hope that it works when combined with parental attention.