I worked in manual labor jobs most of my life as well. As for people that think its okay to feel like a big shot at the expense of others its asinine. Most of the people that work those sorts of jobs can't even afford to eat or get things from the places where they even work.

I've written letters too and in some cases like when I was in the Philippines the pizza was really weird and all of the toppings just slid onto the floor. I didn't eat it, didn't complain, left a sizeable tip and just went somewhere else.