The ultimate problem with tipping restaurant service workers is that servers are legally allowed to be paid sub-minimum wage. The restaurant offloads their obligation to pay their employees onto the customer, and if the customer doesn't tip then the server will not be paid anything for the work. Under these conditions, customers have a moral obligation to tip servers, but that doesn't mean the system isn't a mess. Servers get no benefits, back staff get no tips, but servers get cash and the opportunity to underreport their tax burden.