I didn’t know it either. When I was young “Professor” was a title of honor. When I got my PhD and already had my Doctorate in Veterinary Medicine, I was honored to be called Professor...most people do not know the academic degree of PhD is “higher” than “doctor of medicine” and “doctor of medicine” is equivalent of a BS. No matter what, far better “Professor” than “Mrs” in the professional setting as “Mrs” cooks the turkey and “educated” people speak really slowly to her to make sure she understands. Yes, indeed.
(Please forgive this next "Your Reply"): You did not want to sound condescending to my mother, "Mrs. Loucks." She was the first daughter in her immigrant generation to graduate from high school (also, the first accredited school in Michigan), and became the matriarch of her generation.
She was the embodiment of Proverbs 31; "worth far more than rubies." She was my father's life-long love, mother to four college-educated children, mentor to school children, supporter to the community and her Church.
She was stylish and well-read, had a letter published in Time, could address a political group or a child's poetry class. She marched for Woman's suffrage, along with her mother; and her father (rare). She was more that a "good cook," she could make the various "game" the hunters brought in palatable! Super Lady and a "True Lady."
An MD is not as you describe it. Don’t know where or how you got your information but it is incorrect. One has a bachelor degree in something and then applie to go to medical school....true for veterinary school as well.
https://en.m.wikipedia.org/wiki/Doctor_of_Medicine
Then MDs usually do a specialty along with an internship. Sitting for licensure is a whole different issue