I tire of this argument that users should obviously know they are trading their personal information in return for access to a service. They don't know this. It's obvious in a conversation with any (even lightly) tech-illiterate person that nothing about how the modern internet economy works is obvious.
Think back to the emergence of the web as a truly popular medium. There was no Google Analytics, no FB tracking buttons that follow you around on every web site you visit (that one is particularly egregious - FB users are tracked even when they aren't on facebook.com, and we expect users to just know this?), just advertisers buying a banner ad slot from the owner of a web site. Back then social networking was, what, AIM? That was free and they didn't harvest user info for it. The change has been gradual, and the idea that users should have kept up with every development that led us to where we are today is preposterous.
When this has happened in the past the answer has been clear: knowledgable people come together to pass laws that benefit individual citizens who have neither the knowledge nor time to learn.