I have to admit I kind of inflicted this on my own child. She has her paper diaries, which are sacred, not to be touched, and a box for putting any artifacts she doesn't want me to see. But for any interaction with electronic devices, the rule is "don't do anything you don't want your parents to see. Just assume we can."

But the thing is, her permanent record exists, and I do not control it, so inhibiting her from entering things into it is somewhat called for.