Dangly bits;
1) For a start get rid of the "safety" word to describe the regulator who use that term to justify their actions.
2) CAA sounds nice. They can write the regulations only. (they may need a bit of help from PNG to do this as their last 23 years and billions of dollars have been for nought).
3) Federal Police, aviation branch, police those regulations only. The burden of proof rests with them only.
4) ATSB investigate accidents and work in conjunction with Feds and CASA, BUT, they, only, nobody else, investigate.
5) DPP, only, prosecute those rules found to have been broken by Federal Police that have a case to answer.
So if you shut down CASA, who would do the regulating
See Para 2).