I am not sure why people have singled out New York cab drivers. ??????
My experience of America is that tipping is a way of life, try walking out of a restaurant without leaving a tip.
Regarding this country, I do not consider myself to be tight.
I usually only tip in a restaraunt if I have been impressed with the service,
even then I don't do a percentage of the bill, I just round the bill up to a logical amount.
If I'm honest I would never tip more than 3 or 4 quid.......Anywhere.
I have walked out of many restaraunts without tipping, if something hasn't been right.