To me, it has nothing to do with the amount of work. The employer is supposed to pay his staff what they’re worth. The tip is to compensate lower-paid staff for the extra effort they put in to serving you. Do you tip at a drive-through? I don’t. But if someone makes menu suggestions, brings me the food, fills my water glass promptly, brings me the doggie bag, then I tip.

The only reason I can come up with for tipping the kitchen staff is because demand is seasonal. If the restaurant owner raises pay, it’s year round. The tip only happens when there are customers.