This has worked so far because we don’t have extremist police who apply the law to the letter- they themselves see laws as mostly suggestions
Something most people don't understand is that Australias' sovereign, the Queen, is used to keep embarassing state secrets well and truly out of the public eye. This is an intolerable state of affairs that will hopefully get addressed when she dies, and the Australian Republic movement gets fresh air under its wings ..
Australia has secret prisons, and a star court for the things it doesn't want the world to know. Witness J, K, L, M, &etc.
So does america. I'm not sure how a republic movement could save australia from having these things when one of the largest republics in the world also has, e.g. hundreds of thousands of censored warcrimes on wikileaks and guantanamo bay
The proof is in the pudding: Yemen, Libya, Afghanistan, Iraq, Syria, Nigeria, Somalia, Ukraine, etc.
The USA has exactly this, in the form of the revolving door that connects the Joint Chiefs of Staff with the CFR.
https://www.opensecrets.org/revolving/
See also: https://s3.amazonaws.com/docs.pogo.org/report/2018/POGO_Bras...
Its figureheads give the impression of democracy, but nobody voted to murder 5% of Iraqs population - the generals went ahead and did it anyway.