Really, I have never understood this, and thought about it again seeing the thread about bad tips for Pizza Deliverymen in the Pit.
Admittedly, there are restaurants where the general cost of dinner for two is far higher than in others, and typically the waiters there are more attentive and polite. I suppose you are getting something for your money there.
Consider though this example, at a local off-campus college restaurant I frequent, not at all what one would consider a fine dining experience, called The Berg:
Scenario A - Four people enter, sit down, take menus. A bottle of a good cabernet is ordered, $20. Each of the four orders a steak and salad, at $10 apiece. Meal completed, total cost $60. 15% tip comes to $9.
Scenario B - Four people enter, sit down, take menus. Each orders a mug of beer, $2 apiece. Each orders a bacon-cheddar Heidelburger, $5 apiece. Meal completed, total cost $28. 15% tip comes to $4.20, perhaps round up to $5.
The waiter/waitress does the same amount of work at both tables, but gets twice as much gratuity from the first table. On what basis is this? Even the cook probably did the same amount of work in both cases, I can assure you that a steak at The Berg requires no more effort in preparation than a cheeseburger, probably less effort.
Why do we reward the staff based on the cost of our food? What does this the cost have to do with it? Yes, I am well aware how waitresses are paid, and that they require tips to support themselves. I tip my regular waitresses at Old Chicago very well and generally get what I pay for in good service. All I’m calling into question is the method by which we as customers calculate how to compensate the waitress for her work. Bartenders routinely live with the fact that pouring a $10 glass of scotch won’t earn them a better tip than pouring a $2 glass of house whiskey, it isn’t any more work either way. Or for another example, why would you tip the pizza guy more for a loaded-with-toppings $20 large than a one-topping $12 large? Were the toppings so heavy they caused extra strain on the way to the door for which he deserves compensation above and beyond what he should get for carrying the one-topping pizza?