Compressorstall is right on when he says that the RFDS is probably the most high risk GA operation in Australia.
That is why the aircraft are crewed with only one pilot. Saves lives!
On the other hand the RDFS would be a less high risk operation if it used two pilots - especially at night. You have to ask why many mining companies and corporations insist on a two pilot operation. Safety reasons? Insurance premiums?
The Mount Gambier RFDS Kingair accident would probably not have happened if the aircraft had been crewed by two pilots.