Tipping widely varies even within the U.S. I was raised in New York (Long Island). I always tip well. When we bought our first house in California over a decade ago, I tipped the U.S. Mail delivery woman, along with the guys that picked up our trash. My wife (who is a CA native) was bewildered at that. Same when the guys delivered our furniture for said house. She kept arguing with me that you don't tip for those services.
My argument for tipping is -- when you do it, you get even better service. Our mail delivery person (who has remained constant), always makes sure in the rain that if we have a package, it's not tossed over the fence and sitting out in the rain. She bags it, calls me, and tells me exactly where she put it. Our trash guys don't have my number, but unlike the rest of the block, my garbage cans are always neatly next to my driveway, whereas others' are knocked down, moved a bit, etc.
It's the little things that make it worth it. And we're not talking about a lot of money here. $20 at the holidays, a gift card, things of that nature.
At restaurants, I get tired of the tipping percentages. I tip when I receive actual service. I don't tip when someone at Subway makes a sandwich for me. And I tip according to the level of service. If I get average service, with a person doing their job the way it should be done, they get 15 percent. If they are a bit friendlier, and do a good job, 18 percent. And if they go absolutely above and beyond, I'll even go up to 25 percent depending on the place and what was done (but usually 20 percent).
It goes the other way too -- we once went to lunch at CHeesecake Factory. Our waiter knew the people at the table next to us. He spent all his time chatting them up, never refilled our drinks, never asked how we were doing, didn't show up at all except to take the order and give us a bill. That's shitty service, and the tip reflected that (I gave him 5 percent, and left a note for his manager about where his employee was spending his time). I always tip SOMETHING, however, as it isn't the kitchen staff's fault the wait staff sucks (and all those tips are pooled and shared most times). But if you deliver shit service, you're getting a shit tip, plain and simple.
And no, we haven't returned to that Cheesecake Factory...been a decade or longer now...
Suffice it to say, I believe in tipping for service rendered, and to make my own life easier down the road. And to-date, it always pays off. If I spend more than one night in a hotel, I drop a 20 in an envelope every other day. Always come back to find extras of everything in the room, and clearly, more time spent making sure my room is above and beyond. And that means something...