Indeed. It does seem like a defect in parenting. There is no conceivable reason why you can't forbid your kids from using these things (whether they disobey is

Indeed. It does seem like a defect in parenting. There is no conceivable reason why you can't forbid your kids from using these things (whether they disobey is another matter, but that's life and at least the law has been made known to said progeny; may the punishment begin!). If you can't do that, then frankly, you've got bigger issues as a parent than the inability to forbid the use of these services. Maybe start with those first.