Rule of Retail #9: 'The customer is always right' is a service attitude and not to be taken literally. Those who do take it literally fall under Rule 1a.

Rule of Retail #1: There is always an upset child.
Rule of Retail 1a: If there is not an upset child, there will be an adult ACTING like an upset child.

Actually, by definition a waiter IS your servant.

More important, this does not give you the right to treat them like a slave.