You tip <U>low wage</U> folks like the pizza delivery guy or the waitress. You can offer a cold drink to the UPS/USPS guy on a hot day. You can give then a Christmas card with cash or other gift if you so desire. Some guys clear $1k or more at Xmas. I heard an old story which I don't know is true or not, but supposedly there are two mailman appreciation days (like Xmas for one) in Mexico where you are expected to tip the mailman. And those who don't give, often have trouble getting regular service.
