When tipping extends to the self-checkout machine, who receives them?

Gone are the days when customers tipped a waitress who served them by putting cash directly in her hand. Now, point-of-sale kiosks prompt people for tips — even if the customer didn't interact with a human. 

The problem with tipping at a self-checkout machine is there's no proof the money goes to an employee, Wall Street Journal reporter Rachel Wolfe told CBS News. 

"Machines don't have the same protections as tipping human employees, so while the law requires that something called a "tip" has to go to employees, when you're tipping a machine, you can't be quite so sure," Wolfe said. 

Airports, coffee shops, restaurants and stadiums now have self-service kiosks. And merchants have programmed the devices with pre-set tip amounts — sometimes at 18% or higher — in hopes of generating more revenue, all of which are leaving customers baffled and experiencing tip fatigue. Wolfe said research has shown that customers feel more obligated to tip using a machine  even if they haven't interacted with a human worker. 

Using tips to support underpaid staff

Tips have traditionally gone to waitstaff, bartenders and other service workers who earned the so-called "tipped minimum wage" — federally set at $2.13 an hour — and thus rely on tips to earn the balance of their income. Some companies that pay workers a living wage are still using self-checkout machines and tacking on tips to provide a bonus to employees, Wolfe said. 

"But researchers are worried that companies are using tips as a way to put the onus on consumers for paying their employees rather than raising wages themselves," she said. 

Diane Gottsman, an etiquette expert, told CBS News last month that tipping these days is confusing and she's not opposed to declining to tip for quick transactions. A good rule of thumb is to tip all food delivery drivers, no matter how they bring your food, between $3 and $5, said Brian Warrener, a professor of food and beverage operations at Johnson & Wales University. Otherwise, tips are optional and should only be rewarded when an employee gives exceptional service, Warrener said.