I imagine a couple of things work against this; nobody wants to take the pride hit of working for a small sum of money for awhile. Perhaps they imagine they'll have another high-paying job in a month so it's silly to take low pay for 6mo and HOPE the high paying job comes in after that time. Also, what happens if they can't hack it? Suddenly they probably can't even claim unemployment...

It's a good idea, though, it probably just has a few practical barriers.