Most of the people I know at AA would be screwed without CSs!
Many only work 20 hrs a week to make this part time and work full time elsewhere.
I wonder if US allows giving away half of you hours?
True, but if they are only working 20 it probably means that before OT others are working 60. Both are working 60, the "part Timer" puts in 40 at his primary job then at least 20 at AA. Its still 60 and he is probably still fatigued. Between the two of them they are supplying 50% more labor and contributing to the vicious cycle that keeps driving down wages.
Duty times may only directly affect the guys working CSWs but eventually the guys giving the days away would run out of people who could work for them. The guys giving the days away would probably quit, removing not only their labor but also the ability for the guy to work 60 hours at the lower straight time rate. The company would have to pay OT instead. The company would be forced to try and get more workers and they would have to offer better wages because there would be less supply.