I up-voted you because I wholeheartedly agree that privacy is primarily a UI/UX issue, because the strongest internal privacy algorithms don't mean much in a social network if most people don't use them.

Although I disagree that Facebook's privacy UI/UX is a good one. I almost find it purposefully obfuscated in order to encourage world-readable posting.

And ultimately, the issue with Facebook is how the company operates with user's data, by virtue of being an effective monopoly in the social networking market.