I agree with you that it's silly to think of special laws being created specifically for facebook and the like. The problem with laws in all areas right now is that the internet and everything that came with it is so far "out there" that there's no way that lawmakers 50 years ago could imagine its impact. That's lead to now, where some laws are wholly inadequate to deal with real issues that we face.
In hiring laws, it's the applicants that are getting screwed by the lack of these laws, because their choices are to either acquiesce to the hiring manager's demands or lose the job. While it's easy for some people to say "I'd just walk out," a single mother who needs to feed her kids probably wouldn't be so quick to do so.
In the end, it's a matter of the job market. If the market were flush with openings, hiring managers would have to be on their best behavior for fear of losing a promising candidate. Right now though, that's unfortunately not the case, so it's up to regulation to give people some basic rights. In my opinion.