Does CASA not have Ops inspectors who are mandated to check out mustering operations?
Do the operators have to maintain logs of where and when their aircraft fly? Surely that could be made auditable (subject to unscrupulous falsification of course) such that illegal night flights in non-equipped aircraft by non-rated pilots should be relatively easy to spot and therefore police?
There must be a way of weeding out the 'excessive risk takers' but I guess it starts with a culture change which will have to come from regulation. Either that or CASA just accepts the Darwinesque nature of CFIT as a natural selection for mustering pilots.