Is this actually true? Jailbreaks haven't been persistent in the face of updates in a long while, so for devices kept up to date it's possible to lock down an iPhone fairly hard. I haven't investigated how parent control compares to full MDM, but the supervision capabilities now in iOS [1] are pretty powerful. For better and for worse of course, that kind of control over user devices, particularly in the context of parents and children, is definitely a double edged sword. But compared to typical computers I don't think it should be lightly dismissed either as something kids can just get around. They aren't open systems.
