Hang out with teenagers, or even 20 somethings, for just a little while, and you'll see that privacy means nothing to them. The youngest kids are a little better, sticking to Snapchat over Facebook and Instagram (because the messages are "temporary"). But for example, when a friend of mine got into college, she posted on Facebook, "just got checked in!" along with a picture of her school ID, her room key, and the form with the room number. I told her that someone could easily get into her room with that one photo, but she didn't care.