You'd think that the one safe place that kids have away from their parents is the internet. You can log on to Facebook, make sure you aren't' friends with your parents, and have a blast. That's not the case when your parents are crafty and have found a way to get your password. Maybe they didn't even need to sneak around to find your password though. If you're under eighteen, your parents have every right to tell you that you can't have a Facebook without giving them the password. That's just parent law in action.
Here's one reason to know your kid's password - you can find out where they are by sending out a distress signal. Parents need to watch out though. You don't know what you'll find in the DMs. You might find a message that you're better off not reading.