This discussion reminds me of an interesting story. In the South under Jim Crow, whites were very reluctant to call a black man "Mr.", which made things difficult when they had to discuss prominent people (like Booker T. Washington) who had to be addressed formally. The solution was to emphasize that person's title.

"To an unfamiliar Northerner one of very interesting and somewhat amusing phases of conditions down here is the panic fear displayed over the use of "Mr." or "Mrs." No Negro is ever called Mr. or Mrs. by a white man: that would indicate social equality. A Southern white man told me with humor of his difficulties:

"Now I admire Booker Washington. I regard him as a great man, and yet I couldn't call him Mr. Washington. We were all in a quandary until a doctor's degree was given him. That saved our lives! We all call him 'Dr.' Washington now."

Sure enough! I don't thing I have heard him called Mr. Washington since I came down here. It is always "Dr.' or just 'Booker.' They are ready to call a Negro 'Professor' or 'Bishop' or 'The Reverend' - but not 'Mr.'

https://books.google.com/books?id=QsLQAAAAMAAJ&pg=PA148&lpg=...