Facebook
absolutely violates people's privacy. But you're conflating Facebook's privacy violations with people's "over-sharing" on Facebook. But those two are actually not the same.
Let me give you an example:
1) Friend shares when he went to the toilet. Is that a privacy violation by Facebook? If it's public, then it's not. If it was private, and then Facebook makes it public by changing the default settings, as it's done many times before, then that would be a privacy violation. But forget about pooping. What if you get drunk and post your drunk pictures to your friends and then Facebook makes them public so your boss (or future boss) can see them?
2) Here's a much worse example than that. Facebook is tracking people through the Like button without them even clicking on it. They never gave Facebook the permission to do that (and I mean in a very "opt-in" way, not just by automatically agreeing with Facebook's ToS). Even worse than that, Facebook has been caught tracking people who don't even have a Facebook account and building "shadow profiles" of them. How is THAT not a privacy violation?
So I think people who say "Facebook doesn't violate people's privacy - they just choose to overshare", are either oversimplifying all the issues and conflating them into a convenient one, or are not too educated about the topic.
Oh and if you want even more real examples, Facebook has just been found to infringe people's privacy in Europe, where the privacy right actually exists, unlike in US, where "digital privacy" seems to be treated as an abstract almost non-existent thing, and the laws protecting it are orders of magnitude weaker than the laws protecting "physical world" privacy - even though there shouldn't be any difference between say law enforcement getting your printed pictures and getting your digital pictures:
http://www.theguardian.com/technology/2015/feb/23/facebooks-...