Good grief. What about Germans who called waiters “boy” over since before modern times. And in France where since millennia they call waitrs “garcon” which is boy. Those were all white men.
I'm afraid that you're mistaken. From the 1800s till about the 1950s, the proper form of address for a waiter was "Herr Ober" ("Ober" being short for "Oberkellner" = "head waiter" [even if he was only a busboy]).
Waitresses, on the other hand, were addressed as "Fräulein" (= "Miss" [regardless of her true marital status]). To address a waitress as "Gnä' Frau" (= "Gracious Lady") would have been considered condescending and insulting in the extreme. (Older single ladies were actually proud of the fact that they had been able to stand on their own two feet without the help of a husband.)
Sadly, in post-war Germany, such terms of address have died out, and I am sure that I "date" myself when I "accost" a stranger on the street to ask directions and address him as "Mein Herr."
I visited the U.S. 20 years ago, and was shocked when the waiter came to take our order and addressed my wife (!) and me with "Hi, guys!" (I immediately corrected him, of course.)
O tempora, o mores!
Regards,