There are many problems with selective schools, rorting by coaching - ie training for the entance exam rather than being selected for genuine academic ability - is just one. Asians are used to and prefer rote learning and drill ("don't think, do it our way") and so coaching colleges suit them, hence the disproportionate number of Chinese and Indian pupils. Note the near total absence of Arabs, Islanders, Africans.
White Australian parents have a much more rounded, holistic view of personhood, childhood, development etc so they do not act like Dragon mothers, forcing their kiddies to be at a coaching college until 8 pm memorising test q uyestions instead of doing some sport or play with friends.
The other big problem, possibly at the root of all the problem, is the general low quality of schooling in comprehensive schools. Low ability, low motivation pupils set the tone andeth o s of such schools so anyone with ability and interest in learning soon finds them a boring waste of time. Discipline is low, disruptive, thick pupils and their parents keep standards low.
Anyone with ability and interest in learning turns away from them and send their children to private or selective schools - and so the low ability, low motivation to learn cohort takes over comprehensive schools more and more.
Not satire, documentary.