How would you call a person you don't know? Particularly someone with authority, like a cop, border guard, etc? Just curious; so far I still consider "mister", "man", "ol'guy" and "chap" to be deliberately insulting :)
"Hey, guy..." or "Hey, dude..." or "Hey, man...". I prefer just "Hey" or "Hi" to get someone's attention. "Mister" and "ol(d|') guy" seem anacronistic to me. (I was born after Vietnam if that helps.) "Mate", "chap", etc. are the same idea, but originate in British (or colonial British) culture.
Those attention-getting pronouns are frowned upon in formal or "civilized" (upper-class or upper-middle-class) communication, I suppose because it's considered informal or rude to try to grab someone's attention that way. However, in everyday vulgar (as in not-formal) speech, I don't consider any of them to be insulting. There are other culture-specific race-specific and gender-specific pronouns which can be very insulting, to the point of getting you killed when used in the wrong situation, but can also be okay depending on who you are and who you're talking to.
When talking to cops, border guards, or any agent of the executive branch who has the power to ruin your day, I would always use "sir" or "ma'am".
e.g. "Hey, guy! Don't step on the wet floor"?
I don't think, generally speaking, that honorifics are required, even with individuals working in an official capacity (I would never say "sir" to a cop or a ICE agent, for example). That might just be a west coast habit, though. Back east, things might be different.
BTW how would you talk to the said cop? Officer?
I'm from Southern Europe and I'd say it's quite normal for waiters to greet customers like that (except on fancy, expensive places of course). You don't have to "create bonds" with them, it's just a matter of being friendly.
Also, don't forget that waiters in the U.S. live off their tips, so I guess that can be a reason as to why they try to be as friendly as possible.
When interacting with authority figures I am generally polite without deference.
I find that people generally use honorifics when they're being quite rude and would like to soften the impact (e.g. the perennial "Good day, sir"), or while insipidly attempting to endear oneself to another (e.g. perceiving someone as wealthy or powerful). I don't know if it's my own egalitarian nature, or cultural, but I find both more rude than the omission of "sir" or "madam".
I wouldn't call a cop anything. Would just say "hi".