As a student in mixed government schools, I didn’t really see male prefects as holding much power over me at all. Only surmising, now, but had one of these guys dobbed-in (an Aus expression meaning “to tell on or inform on”) a fellow male student he may well have needed a bodyguard!
One needs to take account of the Aussie culture back then, which had its throwbacks the convict era. For a convict to be “dobbed” could have meant dire consequences including flogging with the cat. Thus, we were told, we developed a certain disrespect for governments and the church but above all for dobbers.