Why are (male) surgeons still addressed as Mr?

Surgeons, or rather male surgeons, are always addressed as Mr in the United Kingdom and the Republic of Ireland, sometimes but not always in Australia and New Zealand, and rarely in Canada or the United States. This curious British tradition is such a mystery to doctors in other countries as well as to the British public, that even a work as erudite as the 1996 edition of The New Fowler's Modern English Usage seems to have got it wrong.1 Is it therefore a tradition that should be perpetuated indefinitely, or should it be abandoned?

To understand how the tradition arose it is necessary to go back to the beginning of the 18th century, when physicians were distinguished by the possession of a university medical degree: an MD. Although many had acquired their MDs abroad with minimal effort or bought them for about £20 (about £800 today) from the Universy of Aberdeen or of St Andrews, the possession of a medical doctorate entitled physicians and no other medical practitioner to be addressed as “doctor.” Eighteenth century surgeons, who were of course addressed as Mr, seldom had any formal qualification except in the case of the few who were Members of the Company of Surgeons. After the founding of the Royal College of Surgeons of London in 1800, however, it was customary for surgeons to take the examination for Membership of the Royal College of Surgeons and put MRCS after their name.2