I don't know whether waitresses get lower tips than do waiters. I suspect it is the other way around, because -- as waitresses have told me -- men tend to be more generous tippers than women. Who knows? One thing that is not mentioned here is that, ahem, waiters and waitresses might prefer to get more of their income in gratuities than in wages, because, well, go figure.
My experience with labor and management in such enterprises as restaurants and small factories suggests that when they work, everybody is happy, and nobody wants interference from outside -- and what we have here is a kind of interference from outside, because it imposes upon the workplace something extra, something not suggested by the nature of the work to be done and not requested by the workers themselves. My mother and my aunts had good relations with the boss in the small dress factory where they worked, meaning that they might put themselves out when an order had to be rushed, and he would give them generous time off during the summer, and if you called in sick, no questions need be asked. You had to treat people well in order to keep the mob-controlled union (ILGWA) out of everybody's pockets. (I am not saying that all unions were corrupt; but the ILGWA had gotten commandeered by the mob, and in the two factories that I had plenty of direct and second-hand experience of, the workers wanted no part of them, while the union tried to force them to capitulate by denying them access to suppliers and retailers.)
There's something else. Imagine that you are going to the beach, to swim, to lie in the sun, to build a sand castle, to go hunting for clams -- and there's a politician in the lifeguard's chair, shouting through a bullhorn. You go away. You try to take a walk along a woodland trail, but every fifty yards you are met with a big bright sign hectoring you about politics. You go away. You go to the bowling alley. There's a big screen above, blaring out Fox News or CNN at you. You try to escape to a nearby church. You break into the vestibule and see it all hung with churchy-political slogans. Then you go mad, quite mad ...