Gratuity is different all over the world, in some places like NYC its a very large portion (if not all) of a server's salary, hence Vinnie(or is it Todd?)'s perspective. Some people don't like having to tip if they're not used to it, but the costs ends up in the wash because you just paid a bit less for your beer anyway, usually. When I'm in a country that tipping isn't usually customary it never fails to make me feel like I'm stealing, haha.
...and now, Infographics! (click here for full size)
|source -> http://www.mint.com/blog/goals/tipping-abroad-03022011/|