I believe that mic is confused about the situation regarding MD and PhD in the Aus and the UK. The two systems are identical. In the UK, we also have higher doctorates, such as DSC (Doctor of science) which are awarded by an individual for their contribution to their field of study. The concept of an MD as a higher doctorate is slightly misleading. This is because those awarded the bachelors degree MBBS, BM, ... etc, are misleadingly referred to as doctors (we are infact honourary doctors and it is the PhDs who are real doctors). Consequently, the MD is clumped together with the higher doctorates. MDs (both in the UK, Aus and all commonwealth countries) are awarded after approx 2 years of clinical research and the completion of a thesis. They are not awarded as recognition for excellence in one's field of study.
Previously, an MD was more revered (in medicine) than a PhD as clinical research was seen as the benchmark for clinicians and subsequently, almost all the older consultants have an MD whereas a greater proportion of the newer consultants have a PhD. With increasing reliance on the scientific basis of medicine, and the general acceptance that a PhD is more focused and technically more rigorous, Phds are now regarded as a higher standard of qualification for physicians who want to become academics. Increasingly however, PhDs are becoming a requirement even for obtaining a consultant post (especially in medicine and its subspecialties)