I'll echo the parent commenter's anecdotes. I'm 43, so I've undoubtedly been exposed to many rude service workers in my days. Honestly, though, I can't remember a single incident. Perhaps that is a clue to my ability to respond kindly, or decently at the very least, and then move on. I'm not trying to "kill them with kindness", I just deliberately avoid confrontation and try to treat people like I'd want to be treated. Golden rule and all that.

Everyone has bad days, and some people are just plain assholes; that doesn't mean you have to treat them poorly, whether provoked, deserving, or otherwise.