Why do people tip a waiter?
Most people have already answered this. Waiters/Servers make $2.13 per hour. The balance of their income is from Tips left by their guest. You are tipping them for the work they do for you. The restaurant could eliminate the need for tipping by charging you more so they could pay the servers what you make an hour. Serving is a difficult job. But good servers love what they do and enjoy making the guest they serve have a great time.