Privacy is a privledge, not a right. If they blow my trust, they blow their privledges. That means, if you want to close your door, don't slam it. If you want to lock it, don't be doing stuff you shouldn't be doing. If you want to go out, then go exactly where you say you are going. When my kids get older, if they want to go out and i won't be there, then i want to know where the place is, who is going to be there, and when you planned on coming home. I would also want them to text me when they got there and when they were leaving. That is mainly for me to feel better, since kids going out and not returning scares me. I do that for their own good.
So far, the kids have a computer of their own and my daughter only uses it to get on her games, she has in a favorites folder. She doesn't know to search things she just plays the games on the websites we saved for her. When she gets older, i will probably check history to prevent viruses, and cyber-bullying. Also, if she has something to hide it will be a big deal. if she doesn't have anything to hide, then it should just be another roll the eyes and say, "Fine mom, go look." and i will just see that she is keeping herself out of trouble and safe. She is minor til age 18, it's my job to protect her well-being and if that means looking through her diary because i'm almost certain she's on drugs, or is hiding something big from me, then she can WATCH me tear through her room. but never will i snoop around while she's at school, and read little notes or stuff that she's thrown in the trash can unless i feel she is keeping something from me that can harm her.