Aren't those name/pronoun mismatches in both cases a clear expression of status gradient? "I consider you close but I certainly don't consider you a peer". I suppose that neither of those drivers would reply in similar form. (though far less unlikely in the munich variant I think). An exception would be a recurring pattern of ironically using the family name like a nickname in youth language. Perhaps male only youth language, but very much an entirely different thing from those Munich/Hamburg oddities.