For as long as people will accept slave wages those employers will continue to get away with it. I was told by a stude who works for the ATO that they will only investigate sham contracting if they are losing more than a certain amount, which had a lot of noughts in it. That was before FWA was in place. There is no excuse now.
It's not just the smaller operators, how about the big behemoths that have gone under and closed down with the staff left high and dry with no super etc.
Salary sacrificing for flying training is something that has to be managed carefully and calculated precisely to be fair.