I started to write this as a comment to a post on The Dictionaly(which is great, by the way), but it got too long, so I decided to bring it over here
About the 10%-20% issue. I wrote in my blog a while back (link) about tipping... When I wait on a table, I'm always looking for 20%... I can understand that people don't want to tip that much sometimes, but the idea is this (keeping in mind that mine is one of the better restaurant situations)...
Lets say I have 5 tables and they all spend around 100 dollars for their meals. Everyone of them tips 20% so I make 100 dollars, right? Wrong, I make 87.50. Every restaurant, some more than others, makes their employees tip out to the bussers and the bar, and sometimes the hostesses. Its just part of the world. The amount you tip out is based on the amount of your sales. This is why it is always nice to tip on the entirety of the bill, and not exclude wine. I still have to tip out on the wine that you bought, if you tip me or not.
So, if all my tables tip me 20%, then I'm doing fine, 87.50 is a decent wage. But if those same 5 tables on tip me 15%, which comes out to 75 dollars, I still have to tip out the same amount, 12.50, I now make 62.50, which is now a huge pay decrease.
Now, while this is a huge decrease, it may not seem to be that big a deal to some people, so let me put it another way. Most servers work 7 hours a shift. So, lets say that I make that 87.50 in a 7 hour shift. I'm now making 12.50/hour if my tables tip me 20 percent. Now, if my tables tip me 15%, garnering me 62.50, then you just gave me a drop in pay of 3.50/hour. That is a huge drop.
Its not an issue of "I did this, I deserve to be tipped a certain way" it is a matter of the economic system as it is set up. You may disagree with the system, but the system is set up that way, and 1000's of people make their living, and subsequently, live their lives, based on that economic system, and it is a bad move for you to lessen their quality of life based simply on your feelings on the legitimacy of such a system.