Another thread has revealed that many DUers -- i.e., self-identified liberals -- think it's OK to tip 10% or less when the service is less than ideal. There are many problems with this.
First, the reasons people give for undertipping are mostly things that are not under the server's control. If the server took too long to bring you your food, it was probably a problem in the kitchen. If the server did not take your order immediately, it was probably the fault of the restaurant owner, who left the restaurant understaffed. Or perhaps a server called in sick and could not be replaced. In those cases, you should speak with the manager, not punish the server or try to send a coded message by leaving a small tip.
Second, most servers in the United States barely make minimum wage, even with tips. This is because the federal minimum wage for tipped employees is $2.13, much lower than the regular minimum wage of $7.25. Although the restaurant is supposed to make up the difference to ensure that every server makes minimum wage, the vast majority don't do so. And many customers, including people who are cheap, Republicans, and foreigners unfamiliar with the system in the U.S., fail to leave any tip at all.
http://www.motherjones.com/politics/2014/05/minimum-wage-tip-map-waiters-waitresses-servers
"The servers who make 'good money' are in the minority," says Maria Myotte, a spokesperson for Restaurant Opportunities Center United, which aims to improve conditions for workers in the industry. She notes that tipped workers are hit especially hard by "wage theft," whereby restaurants don't make up the difference when the tips aren't rolling in. Between 2010 and 2012, the Wage and Hour Division of the Department of Labor conducted nearly 9,000 investigations in the restaurant industry, and discovered that 83.8 percent had some kind of wage and hour violation.
https://www.washingtonpost.com/news/wonk/wp/2016/02/18/i-dare-you-to-read-this-and-still-feel-ok-about-tipping-in-the-united-states/?utm_term=.e6a344286c9d
There’s this myth, especially if you live in a place like New York or Washington D.C., that what tipped workers make is largely even, that everyone makes what white guys working at fancy steakhouses make.
But even in places like New York and D.C., seventy percent of tipped workers are actually women, largely working at casual restaurants, like Applebees, IHOP , and Olive Garden, earning a median wage of $9 an hour when you include tips. These people suffer three times the poverty rate of the rest of the U.S. workforce, use food stamps at double the rate, and, the worst part, suffer from the absolute worst sexual harassment of any industry in the United States. When you’re a woman living on tips—even if you’re making a lot of money on tips, which most women aren’t—you’re subject to the whims of the customer, and really encouraged by management to objectify yourself or subject yourself to objectification to make money in tips.
Third, female and minority servers are systematically undertipped. One reason for this is that the most expensive restaurants tend to have white male servers. Another reason is that many people are sexist and racist and will perceive flaws in the service when the server is a woman or a minority that they would not notice if the server were a white male. To avoid contributing to wage inequality, tip a higher percentage at cheaper restaurants.
http://www.slate.com/articles/life/culturebox/2013/08/tipless_restaurants_the_linkery_s_owner_explains_why_abolishing_tipping.html
Studies have shown that
tipping is not an effective incentive for performance in servers. It also
creates an environment in which people of color, young people, old people, women, and foreigners tend to get worse service than white males. In a tip-based system,
nonwhite servers make less than their white peers for equal work. Consider also the power imbalance between tippers, who are typically male, and servers, 70 percent of whom are female, and consider that the restaurant industry
generates five times the average number of sexual harassment claims per worker. And that in many instances
employers have allegedly misused tip credits, which let owners pay servers less than minimum wage if tipping makes up the difference.
https://www.bostonglobe.com/opinion/editorials/2014/02/17/tipping-system-exacerbates-unfairness-restaurant-pay/XqPSy4UgwgYjhoMWWufzsO/story.html
Women, who make up about 73 percent of tipped workers, are disproportionately harmed. Waitresses in some gritty bars and grills say they feel compelled to flirt with customers and laugh at offensive jokes just to preserve their income. Even then, they earn an average of $0.50 less per hour than male tipped workers, government statistics show. Doing away with the tipped minimum and giving these women a steadier paycheck would be the quickest way to restore their dignity.
Please, regardless of whether you were a Bernie supporter or a Hillary supporter, always tip at least 15%. It's a matter of having empathy for a fellow human being.