Some teens see privacy as a right, but many more see privacy as a matter of trust. Thus, when parents choose to snoop or lurk or read their online posts, these teens see it as a signal of distrust.
(It's Complicated, page 73)
I can remember in 8th grade when my friends' parents starting joining Facebook, not because they wanted to snoop on us, but because they saw Facebook as an opportunity to reconnect with old high school and college friends. However, some people did see this invasion into the "teen world" as their parents mistrust of them. Until recently, my parents have not had any desire to join social media (now my dad has a Twitter that he uses as a newsfeed for short, quick headlines). But more so than social media, my parents' surveillance of me in other ways has given me the same sense of distrust that the teens interviewed in It's Complicated expressed.
Until I turned 18, my dad received a text message every time I used my debit card, including where and how much. They also have the ability to (and they do) use the location services on my phone to see where I am. In short, if I wanted to go somewhere and do something without my parents' knowledge, it wouldn't be easy. Sometimes, it would seem that they don't trust me to tell them where I actually am and what I'm actually doing, but I'm sure their intentions are to ensure my safety in case anything were to happen.
In high school, I gave up some privacy to appease my parents and follow their rules. But now that I'm at college, our understanding is that unless I go off campus anywhere further than walking distance, I must let them know where I'm going. In other words, they trust me and give me the privacy to go and do what I please around and just off campus, and I expect that they won't betray that privacy by checking my exact location all the time. I think that in all aspects of life, the balance of privacy and trust versus safety and protection is an integral piece of the relationship between a teen and his/her parents. Even if we have nothing to hide, we associate having some privacy with the extent to which our parents trust us.