It’s one of those things that would help in a mass coordinated action, but accomplishes nothing and does harm as a solitary act. I’ve never seen anyone even suggest a mass coordinated action on this, which leads me to believe that most people who don’t tip out of “protest for the system” are actually primarily motivated by saving themselves a buck, since that is the one thing it accomplishes. See, I have “thought about it,” and I don’t think people who don’t tip truly have.