Well I was going to give an explanatory reply to this... but
@maxxor said it for me... so I will just add...
I have worked at hospitals where my paycheck is a direct result of the billing for that shift. Usually it's a 2 month lag time (so in March I get paid for the patients I saw in January). At those sorts of jobs there is wild fluctuation in the paycheck from month to month based somewhat on patient flow, somewhat on acuity, but affected the most by payor mix. I'd usually run 20-30% unpaid or unreceivable bills in a month. I had a (thankfully) anomalous month where over 50% of the bills generated didn't get returned. But despite the sudden drop off in income I still had the same bills at home, the same malpractice insurance costs, the same lost-time with my kids... but wasn't getting paid for the entirety of the work I did.
So yes... someone has said to me "well sorry, this patient doesn't have insurance so we're dropping your pay for this shift". They just didn't use those exact words but the end result was the same.