So how does CASA determine for itself that you are a fit and proper person to hold the licence?
CASA does this via a network of delegated DAME's. The trouble is that CASA neither trusts them, nor the specialists to whom they seek additional opinion, nor the drug companies who make recommendations about side effects, etc, nor indeed the FAA who publish a much more comprehensive DAME manual than CASA.
Instead CASA centralises all decision making and review, but employs people with inadequate qualifications or experience, thus they have guidelines & protocols provided. But these are inadequate, contradictory and incomplete. And none of the administrative staff will take responsibility for going outside the guidelines (more than their jobsworth). So anything that is not black & white, enters a spiral of review until the pressure for a decision finally becomes overwhelming.
All CASA needs to do is:
a) harmonise its medical standards with other Australian bodies / overseas agencies. Australian aviation does not need unique standards for blood pressure, blood sugar, etc.
b) make the DAME guidelines clear & easy (or copy the FAA one)
c) allow DAME's to have proper authority. They are well qualified, serious people, seriously, why can't they be the arbiter of who is fit to fly? They or their colleagues do it for driving, boating, scuba diving and a range of occupations. As much as we would like to think otherwise, pilots aren't a special breed.