I know they do, because I've seen a friend of mine say "I'm not tipping no guy," as though somebody might think he was gay for tipping a male server.
The worst part: my friend had been in the restaurant business as a line cook probably since he got out of the Navy in the early '70s. He was on the Ranger 10 years before I was.
In addition to black folks, DAR women, and single old men, they don't like to wait on people who only drink water. They reason that people are drinking water because they can't afford or are too cheap for anything else, so why would they tip?
My meal was $16.91 today for chicken strips, fries, and cole slaw. With water. I tipped $5.00, as I do everytime I go to the place where everybody knows your name. Unless, of course, I'm buying lunch for someone else. Then, it's still 20% of the total; not the net, which it probably should be.
In fact, about once a month or so, I go to Navy Federal and get a $100 worth of fives, specifically for tipping.