The biggest thing to consider here is that “boss” or “big guy” or “buddy”, when speaking to a stranger, can denote many different connotations and any interaction (again, in the states particularly) can become an assertion of power when used a certain way. To a lot of folks, calling someone boss or buddy when you first meet them can be perceived as flippant. For instance, you wouldn’t say “what’s up, boss” when meeting a personal hero, but you probably would to a toddler. Even a greeting like “hey, man” denotes less of a subliminal power struggle to a stranger. I think OP is valid in that the first greeting that someone uses toward a stranger will typically illustrate how they perceive the other person, and “boss” can carry more weight than just a friendly title. It sort of emits this ironic aura that when used on a stranger is in no way endearing.