tink, of course you are right.
What I think we have to consider too, is WHO those waitresses are. Probably not very educated and experienced in life . So, they just go with their basic emotions, they do not think very much further(which I think is demonstrated here pretty much every day).
So, there you have it, that is why you get what you get.

Mabe, just maybe...even if they were treated fairly, a thing like a husband or boyfriend upsetting them may throw them completely off track, and again they would let their emotions take over....lack of professionalism is rampant.

I have seen this kind of thing rather often with domestic staff.