A problem with all of the responses here is that they swing and miss at trying to find an allegory that matches this situation, and then conflate their allegory as truth, losing any of the nuances of the Facebook situation.

You can skew these examples to make your point stronger, too. (The Radio in the restaurant is listening to me!)

The only situation that matches is the exact one at hand: Facebook tracked user information in their share/like widgets. Is that ok under the law? It wouldn't surprise me if it was, but I don't I think the laws should be tightened up on this as well.