Remember George Brandis? The pompous, bungle-prone lawyer who confused spouting Latin with actual legal expertise? These days he's High Commissioner in the UK. But back in 2015 he was the attorney-general who didn't understand data retention, in charge of implementing data retention.
One of Brandis' key selling points of the mass surveillance scheme was that not only would it not increase the surveillance powers of security agencies (rather, Brandis argued falsely, it would maintain the status quo that existed before the internet made it harder to get telecommunications data), but that he would reduce the number of agencies that could access metadata.
That was in line with his claim, and that of security agency bureaucrats, that the scheme would only be used for the most serious crimes (a claim unfortunately destroyed when the AFP commissioner Andrew Colvin said he'd be using data retention to pursue "illegal downloaders").