I am definitely old enough to not succumb to pressure and tip if I didnīt want to.
The problem is, in the US, is that I can imagine that if you donīt tip the pizza guy enough, he might do something disgusting to your next delivery

.
When we order food, and that is once or twice a week, most of the time the delivery person gives me our food and turns around to go back down the 80 steps leading up to our appartment. I have to be quick and call them back so that I can give them their well deserved tip of €3-€5 just for climbing all those stairs.
They donīt expect any tip, but always smile and say thanks