I never really understood the whole tip thing, isn't this exactly what they're getting paid to do?
My personal belief is that it is a scheme for employers to pass on an expense to the customer.
Ideally, a valet, waiter, bellhop, delivery guy, sushi guy etc... should get paid a proper wage (As is the case in Europe). However, there is only so much that the establishment can charge the customer, and so this scheme has been invented where the employer is legally allowed to pay a waiter 2 bucks an hour, and rely on tips. (If I am not mistaken, tips are considered income and are taxable).