"The reputation for black folks being the worst tippers, and even non-tippers was true according to her experience, and not just a trope as many of the defenders of minorities will claim."
I can second that from personal experience. Even my fellow waiters who were themselves black, wanted nothing to do with them.
My Mom was not racist at all. She literally loved everyone and was the nicest sweetest person. But she mentioned in passing on more than a time or two when the subject came up that black folks didn't tip much, if they even did at all, but they were also the most demanding, unruly, rude and unreasonable people to wait on. She said it was well known in her restaurant, and no one wanted to take the tables where blacks were seated, of course they did and treated all of them kindly with the respect afforded to all of their patrons, but they never looked forward to taking those tables for all of those reasons. Any guy in a tank top would not have been allowed to be seated in that dinner house anyway.
Don't get me wrong, many black folks are fine and really good and nice people and they tip wait staff as well as anyone else, and it's a shame they get tainted with the reputation that other blacks have given them.