I don't have any movement numbers however I was part of the team that introduced the multicom frequency of 126.7 to cover all strips which did not have a different allocated CTAF.s.
It was based on a proven safe system from the USA and Canada. It allowed Australia to move away from the very expensive duplicated FS and ATC system that existed prior to 1991.
Saved our aviation industry over $1 billion since then with no measurable reduction in safety.
Creamy I don't think that CASA actually knows why they are insisting on this different system - notice how no individual is actually identified with the requirement.?
I believe it will eventually cause an unnecessary ATC incident or accident as ATC separation frequencies should be free of non directed communication.