That, and the fact that there are many jobs that could be done with some value. Picking up trash in a rarely visited park may not be worth $7.25/hour (presumably if it was, that job would already be being done in today's economy), but it might be worth $0.90/hour. Or maybe it's worth $2.34/hour or $7.23/hour.

I don't purport to know the answer which is why that number is a random variable.