This subject has previously been done to death on PPRuNe - read by all, the advise ignored by most.
If there are any true "contractor pilots" in accordance with Australian tax and industrial law, it would be no more than a mere hand full - if that! A pilot for example, who ferries various aircraft in the private category, for numerous individual owners, may be deemed a "contract pilot".
Those employed regularly (or even irregularly) by one operator in the GA industry are "casual" or "part time" but are not "contract pilots".
"Casual" and "Part Time" pilots are covered by the relevent Award.
Employers of these "contract pilots" should be reminded their legal obligations go back six years if ever a purported "contract pilot" decides to have a chat with his local Industrial Relations Inspector or Tax Office.
Woomera