Parachute operations in Australia are explicitly defined as a private operation. Even though drop zone operators can and do charge members of the public large sums of money for tandems and AFF courses parachuting ops are still classed as a private operation.
To pilot an aircraft on a private operation requires a PPL or higher licence. (Although some people may be able to argue that you can even fly parachute ops on a GFPT if you dont go too far from the airport.)
The employment arrangements between the jump pilot and the drop zone operator are none of CASAs business. A PPL jump pilot can certainly be paid for their services. This is not against the rules.
To go back to the BHP example, BHP could, if they chose to, employ PPLs to pilot their aircraft. This would be entirely legal since a bizjet which is not being used by other people or businesses in return for money is classed as a private operation and only requires a PPL or higher pilots licence. There would be no legal impediment to the PPL bizjet pilot(s) being paid for their services.
The only time that the Civil Aviation rules have any interest in the financial arrangements of the pilot(s) (and assuming that the pilot is not also the operator) is under the "cost sharing" rule which allows all the people on board a private flight (including the pilot) to contribute equally to the cost of the flight.