Why do those with only a Bachelor's Medical degree call themselves doctor? Why do they stop calling themselves doctor if they become surgeons. If is only a soubriquet why don't we have Lawyer Smith and Architect Jones for example.
After all a lawyer cannot practice independantly until they qualify as Solicitors or barristers. Until they do they are merely graduates like the rest of us!!
Mr Spudqueen (who has a doctorate in physics) says that the Doctor title that medical people use is only a courtesy title. When they get higher up they like to be called Mr (or Mrs or Miss) as it distinguishes them from all the 'ordinary' doctors.
Because it is both an honourary title and a profession, surgeons use Mr/Ms for a number of reasons one of which is clarity so that you know whether the doctor is a specialist in medicine or surgery
Doctors quailify with both MB BS, bachelor of medicine and bachelor of surgery and are QUAILIFIED as soon as the degree is conferred