When a government issues secret orders to violate people’s rights, it comes with a gag order. So not only are Apple and Google heavily incentivized not to reveal privacy violations, they’re legally required to keep it a secret.
Really the only reason Big Tech does what they do around privacy is because of public perception. They want their corporate clients to feel that the client’s privacy comes first.
The government approach of legally protected conspiracies against the public aligns the incentives so that there’s pretty much no reason for Big Tech not to cooperate. They will be destroyed (domestically) if they refuse, and they will likely never see any consequences if they cooperate.
And even if they are caught (through extralegal means like hacking, leaks, etc) the conspiratorial nature of the regime makes it hard to single them out. After all, presumably everyone is doing it. Even the company which public postures as refusing to go along with such plans and is publicly reprimanded for their non-compliance could easily be cooperating behind closed doors. By destroying the capacity for civilian oversight, they also cripple the possibility of mobilizing on a case-by-case basis. All we’re left with is the vague sense that the government and corporations may-or-may-not-be fucking us at any given time.
The upshot is that what Australia is attempting is in fact very possible, and the only thing that will stop them is determined disobedience on both civil and technical fronts.