I don't know how it is in Australia, but in the U.S. we have teacher union rules that prevent those with math and science backgrounds from teaching in public schools. (Public school teachers have to major in "education" in college, with a mind-numbing course of study that chases away most people who have intellectual talent and drive.)
Then, when the results aren't good, the teacher unions say we need to pay the (unqualified) teachers more money.
It's an amazing scam on the taxpayer, and one that never fails to work.