There are few workers I feel sympathy for as much as waiters and waitresses. It's often a thankless and very difficult job. Because of idiotic loopholes in the laws, a restaurant can still pay a waiter or waitress much less than minimum wage, expecting that the server will make up the difference through tips.
For myself, I rarely tip less than 20% because I know how tough a server's job can be. To me, it's just a social contract. So you can imagine my utter dismay when reading about a pastor who made a horrible comment on an Applebees receipt containing an 18% gratuity added for a party of 8 or more: "I give God 10%, why should you get 18%?"