I've thought about this a bit and because you're encouraged to think you're in control of your hours, that it's just "being sociable", that you work with "Forever friends" that it encourages you to not consider just how many hours of work you are doing for the measly rewards.
If I worked 40 hours a week and got £500 a month for it, not only would it be illegal, but I would be mighty pissed off.
And people seem to have an up line who can be rather like a boss, in fact worse because they aren't controlled by the law.