I'm puzzled by your second-to-last paragraph. To me it seems completely valid to give someone money for saving me time/effort/discomfort. And most people with half a brain understand how delivery people and waiters are paid (ie below minimum wage, with tips constituting much of their income).

I tip really well, probably more than I should considering that I have so little money. But I don't order in too often anymore, either. It's usually about 20-25%. Will round up to make the bill a nice even number. I've only paid/done the tip at a restaurant once ever (...yeah), and that girl got a RIDICULOUSLY good tip because I'd just been paid, in cash, and she was a good server. It's fun to make someone's shift better if you have the means to do so. Of course, this is part of why I'll never be a millionaire and have serious means to do so.

Have never refrained from tipping, although I thought about asking for one back once. (Jimmy John's took ages and forgot my cookie! But I only realized after the person had already left.) It's a tricky thing because most food services rely on a chain of workers, and you never know exactly who's at fault... but many people prefer to shoot the messenger and leave it at that.

Now I have a question for you: are all delivery drivers male, due to the danger issue?
I've thought about trying to get that as a part-time job (I like driving and am good with directions), but if it's that dangerous or just automatically restricted to males, I guess I won't bother.