1. They depend on tips. Usually most pizza drivers make less than minimum on the road and make less per mile than it cost them.
2. Any order that is late is usually not the drivers fault, as they just deliver.(much like your ups guy isn't actually responsible for your delivery being late)
+ If you call and complain, domino's will give you a refund/new pizza if your complaint is valid.(well most will).
3. Be decent. A two dollar tip isn't going to break you. If you can't afford 2-3 dollars tip, don't order. No driver is going to care if you say "have a nice day" and you stiff him. In fact, that is almost more of an insult because you are fake in wishing well to their face.
4. This is kind of important, they know where you live. Not in a hostile threatening way, but really, if some psycho got super mad because his life was in shambles and you were the last straw, he has your address and access to where you live.
(You wouldn't stiff a waiter and then tell them where you live would you?)