Most users accepted this as a fact. Behind the scenes and not transparent to the user FB was allowing much more access. Now they are understanding the implications.
Not everyone is a highly technical person and to lump everyone into this category is not right. Try explaining this to elderly users.
I think the right way to think about audience controls on social media posts is as controlling who you affirmatively include in a part of your life, not as a way to actually keep any secrets.
For example, you might post pictures of your college reunion, and not share them with work colleagues because you want to maintain a more professional kind of relationship with them. But you shouldn't expect any confidentiality for things that happened at a 200-person event.
A real world example is meeting up with your friends at the bar and running into a coworker. You aren't prohibiting your coworkers from seeing you out with your friends, but you also aren't affirmatively sharing that part of your life with them. And what is appropriate to coincidentally be seen doing is different than what is appropriate to actively share in certain contexts.
Not everyone is a highly technical person and to lump everyone into this category is not right. Try explaining this to elderly users.