The thing is, the restaurants use tipping to augment the pay of other employees too. It's not just waiters and bartenders who get paid less than minimum wage by the owners. The bussers, hosts, and various other positions are paid less than minimum wage, and the difference in pay is taken from tips received by servers. For example, where I work, 4% of my sales are taken straight off the top by the restaurant and used to pay bussers, hosts, to-go servers, and oyster shuckers. Whether you tip or not, I'm still paying the restaurant the same amount of money.

And beyond that, waiters are doing a lot more than than "taking two plates and 4 beers." We are also cleaning your glassware, stocking your beers in the coolers, changing kegs, prepping some of your food, keeping your table clean, stocking the kitchen, etc. Serving tables is a lot more than standing around waiting to drop off food. There ain't no such thing as a free lunch, or an easy job.