If you've never worked as a waiter or waitress in a restaurant, you may think leaving a tip is an optional gesture, something that you only do when a server delivers your main course at precisely the moment that your hunger pangs are reaching their apex, or else jumps in and successfully performs the Heimlich maneuver to dislodge a life-threatening hunk of prime rib from your throat. But if that's what you think, you're not seeing things from the perspective of the 2.26 million waiters and waitresses in the U.S., who are paid an average wage of just $18,330 annually [source: Bureau of Labor Statistics].
For them, that 20 percent gratuity may make the difference in whether or not they'll be able to pay their rent or afford a pair of comfortable shoes to ease the discomfort of being on their feet all day. And servers work pretty darn hard to maximize their chances of getting that extra few percent that can lift them above penury. If you wonder why they introduce themselves by name, it's because research shows that they'll typically get a 23 percent tip if they do, as opposed to 15 percent if they remain anonymous. (Similarly, that odd gesture of squatting down to talk to a customer typically results in a 3 percent additional gratuity) [source: Lynn]. If you think, "The restaurant should just pay its staff more," also consider that if that were the case, chances are the restaurant food prices would be higher, too.
Remember also the other people who provide services to you, such as parking valets, coatroom attendants, bartenders and pizza delivery workers who are heavily dependent upon your generosity [source: CNN Money].