Tipping in America is as necessary as breathing the air around you. Nobody can survive without the dull looking one dollar bill. There is a reason the US has stuck with this crispy green toe rag of currency. Without it, the service industry would die. I suspect there would also be a lot of confusion, and people mindlessly walking in circles and bumping into each other. Americans love the one dollar bill. They adore it. They count them in front of you, and they count them behind you. They have jars for them. You leave them on tables. You leave them on trays. You curl them up and hand them over discretely. You tip for drinks and food, you tip after you eat. Sometimes while you eat. You tip taxis, doormen, porters, waiters, barmen, even the stupefyingly bored looking man who sits on a stool in the male toilets and offers to squirt pink soap on you, and then hands you a towel once you've managed to wipe it off.
But there is a saying in America for those who don't tip. It goes something like this: ASSHOLE.