Roger, you may be correct under industrial law, but overlook requirements peculiar to civil aviation and the functions and obligations of a commercial pilot engaged in air charter or RPT operations.
1. An AOC holder is required to insure liabilities in accordance with the Civil Aviation (Carrier's Liability) Act;
2. A "contract" pilot may not practice his trade in an independent manner, but must operate in accordance with each operators accepted Operations Manual.
3. CAR and CAO requirements at least for air charter and RPT require greater than a casual relationship between an operator and pilot.
It may be possible to engage a casual contract pilot for aircraft ferry, private or aerial work operations. I do not believe it possible to engage a casual contract pilot to conduct air charter or RPT operations.