It is for the same old reason that I left the RAAF so many years ago...
If the Government would pay the RAAF and other military pilots the same as, or better than Qantas pays its pilots, then the military would not be short of pilots.
If you spend billions on military weapons and equipment but only pennies to the men who operate and maintain them (very often under onerous and life-threatening conditions), then you should not be surprised to be out-bid by civil commercial business for the skilled manpower.
But we are now run by Commonwealth and State Governments that are so incompetent that they cannot even maintain a Health system to meet the basic health needs of the population.
So I suspect that based on past performance and current incompetence that nothing is likely to change.