Given that aircraft do not necessarily crash on an airport, I would have thought utilising the local State RFFS, with a permanent station at the airport, would have made more sense.
The fire people would then be able to rotate, and be both practised at putting out fires and trained to fight aircraft fires, wherever they were...
This would remove ARFFS from that disaster area called Airservices Australia, put the airports in charge of what is, after all, an airport service, and have practised fire people on hand if there was an incident.