No restaurant ( or any other business, for that matter ) should be hiring and paying it's employees on tips alone. Yes, I know it happens, but it shouldn't. That is KLflyerRalph's point, which is quite correct.

However, a waiter or waitress does not order restaurant supplies and foods stocks, cook, or prepare your meal. They prepare a patron's table, take the order, serve beverages and the selected meal. They are also trained and expected to voice any displeasure one has, if it occurs, on up to the next level.

If one has a problem with restaurant service, or the meal quality, take it up with the manager, before the bill is settled. That is the appropriate person to discuss and resolve any complaints.