It’s good that the ADF can support logisticaly with water tankers fuel tanker communications and drop in food supplies ( the young ones would like to a rat pack of two) but the ADF have only really got a small cadre of staff trained to fight fires but the majority are not trained to fight fire or have the equipment that could survive the onslaught of a bushfire I’m not really sure what calling up 3000 reservists are going to do.
It won't be front line firefighting; it'll be logistics, comms, some engineering support, general duties 'stuff' and supporting evac centres. All the behind-the-scenes stuff. Frankly, there isn't a huge difference between a fight and a fire - just replace RAInf and RAAC with RFS. In no way do we want to be on the front line (damn, my cam's aren't even fire-resistant!) but we can do all that 'stuff' that a Fire Brigade / SES just can't do (ie, everything beyond intimate support / 1st line).
The reason for reserves is likely due to two factors - the proximity (the reserves are already in NSW and Vic as opposed to most of the ARA) and balancing the ARA demands between readiness, existing commitments, additional HADR and the fires.
It actually offers an interesting example of Reserves for the ADF. To say that we have under-invested in this area doesn't begin to describe our woeful financial, intellectual and strategic failure. Ignoring the issues not having reserves and what that means for mobilisation and the ability to actually do our primary job, the potential to aid in circumstances like this doves neatly into the purposes of the Reserves. I used ARA above - because the other two don't have them anymore (and the hierarchy within the ARes is too interested in themselves to actually change to meet modern needs).
Why, for instance, are the Air Mobility Group aircraft being flown by RAAF personnel? The men and women within AMG face one hell of a work-load already - for tasks with no tactical issues within Australia the level of training needed goes right down - why not use RAAFR people? We lose pilots every year, have them in the RAAFA and scattered around Australia (like they naturally will) and hey presto - the AMG aircraft can fly while the AMG people get some rest. The same can be said for Choules or Adelaide and the RANR.
Obviously this needs fleshing out. The skill sets are technical and would need close management, as well as likely issues integrating "maintenance of skills" training with the normal training and battle rhythm that the regular unit needs/does. There is a cost that will have to come at the expense of something (noting that normally my first question when faced with "we need XXX piece of kit" is 'what are you giving up?'). There is also a clearing out of senior ARes hierarchy and the need to build new ARes/RAAFR/RAN hierarchy which will come at a personnel cost as well as a financial cost. But.... we might be able to build some actual mobilisation for our real job as well more flexible response options for HADR within Australia (and possibly the region).