I have heard of associations fining their members and then get into hot water. The arguement is that since we are "independant contractors" we cannot be fined. If an association "fines" someone, that can be interpreted as an employee/employer situation, in which case unemployment taxes and such should be paid. There was a situation like this somewhere in the country where the state went after an umpire association for 70k in back taxes.
I'm not a lawyer, just an FYI.
As far as working solo when two should have been there ... one guy, two sets of responsibilities. I'm getting at least my game fee and half of the other or they can have zero umpires and save all the $.