CASA's argument, as put to me by the head of avmed, was that DAMEs would be exposed to much more liability and thus have to charge more to cover their insurance, if they were to issue their own medicals without the intervention of AVMED.
On the other hand, for simple medicals (ie everything passes) I think that I can tick the boxes just as well as somebody in avmed.
and on the gripping hand, I'm told that Australian DAME training (all of two weeks) is much easier to get through than DAME training in other countries (eg NZ).