Not everyone is capable of being self-employed. A lot of people are willing to work hard, but need the structure of being told when and where to show up, and what to do.
The fundamental nature of any transaction is that when one party is in a tough position (the formal term is having a poor "best alternative to a negotiated agreement") that person is going to get screwed over. When your BATNA is to have your kids go hungry, most decent parents will gladly give up their own dinners, let alone their Facebook password.
Everyone can do at least odd jobs to reduce the impact of being unemployed. The general point is that you want to maximize your strength so you can negotiate from the strongest position you can....
I can completely understand why someone would hand over their passwords to a prospective employer when asked. There is a huge power differential as you point out. However it is no less stupid.
Here's a basic rule I try to keep in mind, and I think it is extremely important in a hard job market as well, and that is to keep options open and work on ensuring you aren't on the bad end of such a bad exchange. The way you do this is by doing what odd jobs you can to put food on the table, so that even if you need the job you don't need it so badly to take a shit deal.