Getting mad at somebody because they didn't tip you is silly. I do understand how little delivery guys make, but it was your choice to take the job. Why should I be paying charity money to you? Now I never get delivery anyway so it's no problem to me, but why such hatred? Most places already charge 2 extra dollars for deliveries. Where does that go? I might as well make a Digiorno, Red Baron, etc. frozen pizza. And that is exactly what I do. It's the same reason I hate going to restaurants, but there it's worse because I have no choice but to tip. At least I get the choice with delivery to pick it up or not. Still, you get too angry and you will get yourself into trouble one day. Be careful.
Note: I do tip when somebody brings me something. I'm not an un-grateful bastard, but I can tell when someone comes off as angry, and they will get a smaller tip. I don't look at the car either, but the person giving me the pizza. It's shallow to judge the delivery guy on the car.
2001 Taurus SES - 150,100 miles - The new child
1999 Mazda 626 - 156,100 Miles - Slow and steady