That attitudes of some our our non-American members in this thread are absolutely outrageous. Some of you sound like the type of people who go to Italy and demand your pasta as a side dish and not a first course, yelling at the waiter to follow your custom instead of their own. Or like this one British couple I saw in a Mexican restaurant demanding dinner rolls, unable to comprehend that all they had were tortillas.
Come to think of it, when I visit Britain, I think I'll drive on the right side of the road because, goddamnit, that's the way it should be done. The government should change it to the "right" way, and we should give them a nudge by crashing into innocent motorists.
Does it make you feel any better if we don't call it a tip? Let's call it a fee just so you can stomach it better. When going to a restaurant in the US, you have to pay a service fee, and guess what, you get to choose how much it is. The fee should be between 10% and 20% of the bill. Our taxis also have fees like this. Depending on how good the driver is, we give a couple dollars in this fee. We have lots of other "culturally expected fees," so if you ever plan on visiting the US, please buy a tour book and read the section on tipping very thoroughly. And if it makes you feel better, just cross out the word "tip" and put "fee."
Seriously, if you can't handle doing a little math at the end of your meal and still pay less for a meal here than in Europe, then just don't bother coming.