When I worked ER we thought it would be fun to put a coin operated machine in the lobby. You know the "claw" kind where you can try for a prize. In it we would have unmarked bottles. Sometimes ya get percocet ect, sometimes ya get biscodyl or other mundane med. The revenue for the hospital would just roll in, hey and talk about laughs!!
I worked per diem (same thing as you were talking) and we only get 12% more of base pay. That works out to under 3 bucks an hour. I accepted a position that has benefits now. It just didn't seem to be equal.