Flying in to NYC tomorrow and totally looking forward to it, except one thing. Tipping.

A couple of people here tell me that tipping people in the U.S. is expected rather than for good service. I'm shocked if that's true. My own thoughts on tipping are that if you provide over and above what I was expecting then I'll tip you as a thank you. Over here if a taxi driver is a grumpy git and doesn't want to talk in any way = no tip. If I have a meal and it's as expected then no tip. I've been told today that everyone expects tips.

Reality please guys?