I’m not so sure filling the positions is the problem. Advertising them seems to be, though...
The reality seems to be that we spend far too much on defence for the return the tax payer receives. That is not defence’s fault entirely many issues seems to be pressed upon it, ie: a virtual entire Navy that must be assembled in Australia because of ‘jobs’ at only 300% of the cost of the same ships built elsewhere. Political imperatives to maintain a geographically dispersed ADF (and more to the point a massively expensive and dispersed Defence Estate) largely absent from the major population centres.
Allowances on deployment that just send pay-packets through the roof, particularly when combined with deployment durations because there are barely sufficient forces at home that can be cobbled together to replace the force in being. Large retention bonuses to have serving members stay in the force, when they are sick to death of horrible postings far away in many cases, from their families.
Yes this is partly a feature of our nation’s geography, but we chose for ‘strategic reasons’ to ‘pivot to the north’ when the bulk of our population is in the South East and will remain there for the forseeable future...
We struggle to man our major national military deterrent in large part because we choose to base it as far away from our population centres as we possibly can and still have it sited on the continental landmass.
It is a peculiar arrangement we seem comfortable with...
You would be surprised how many service personnel, and their families, enjoy the "remote" postings and happily apply for double postings to stay, or even discharge to avoid leaving.
300% premium for local construction, mmm... no, never has been anywhere like that and has always had more to do with inconsistent procurement over decades than any failing of Australian industry.
One you missed is the serious costs associated with consultants and private contractors who are quite often ex ADF anyway and would be doing the exact same job for less money had the government not decided to "save" and civilianise then privatise the position. Defence is shedding several thousand APS to "reduce costs" when APS are cheaper than uniforms, who in turn are cheaper than private contractors and are usually the same people doing the same job.
In a nutshell APS, ADF and contractors do the same support jobs that were once primarily carried out by the ADF, with some APS support alone. There are far more private contractors than Uniforms in the roles and many more uniforms than APS, yet APS are the cheapest, followed by uniforms with private contractors the most expensive. Uniforms are paid more than the APS because they need to be able to deploy and as such have more demanding requirements placed on them, over and above their civilian equivalents. Private contractors however are paid more than either APS or ADF and are specifically contracted to do only specific things that they can not step outside of.
The really sad thing is many of the senior technical service members are lured away from the ADF by the financial and personal benefits of contracting (they are actually usually full time permanent employees of major defence contractors), instead of staying in uniform and coaching and mentoring junior service personnel.