My oldest son is a bartender/waiter in a college town. He works at one of the chain restaurants. Some of his frequent customers are the professors from the university. My son says these professors are the worst tippers as a group. One guy in particular irritates him. This professor comes in often giving all within earshot a hearty dose of his political philosophy. The liberal professor holds forth on Trump, economics, and the so-called "living wage". And never, no matter the size of the bill, tips more than $2, says my son.
Waitstaff and bartenders are paid in tips. Their minimum wage is a fraction of the federal standard and most restaurants only pay the minimum wage if the tip amounts are less than the hourly minimums. It is either/or for the worker. Most establishments get rid of servers who cannot pull in more in tips than the paltry minimum wage. So when this blowhard tips a measly couple of Washingtons on a $50 tab, then he has cheated the server. Not only did he not pay the worker for the effort. But he took up a table that might have tipped better.
I am in no way arguing you should generously compensate bad service. I do find it hard to believe this one guy gets substandard service every time he dines at this restaurant. If he does, he should not continue to patronize the business. I think we all can deduce this liberal professor is like a lot of progressives, he likes to spend everyone else's money, but is hypocritical when it comes to real life situations. Talk is cheap, apparently this blow hard liberal is too.