Just because a child is doing things they are not suppose too does not always mean that the parent has neglected to teach them right from wrong, or how to be safe. Sometimes the child just chooses to ignore the parents teachings and do what they want. Not all kids are innocent little people that just happen to do something wrong because they were never taught not too.
Kids don't do wrong because they don't know any better. sometimes that's the case but I would venture to guess that MOST of the time it's because they are being rebellious or think they can get away with it.
you can do everything right and still end up with a rebellious teenager.
not that I'm advocating putting these devices on just to keep tabs unless that is nessecary