I suspect the high tax no longer has much of a harm reduction/uptake suppression utility, and that the Aus government secretly knows this, but they are hopelessly addicted to the revenue so will enact overbearing new laws to protect the income stream.

Well that depends…at what point is the revenue stream under threat because of the significant price disparity? My understanding is that it has dropped significantly, which one would imagine is a cause for concern if revenue is a key consideration.