The public education system isn't fit for purpose & it isn't just about funding, that's a convenient smokescreen. Private schools provide a better education for students but that's not purely down to funding.
The whole culture & attitude towards education from teachers, headmasters, parents, unions & children needs to change if the Australian public education system is going to be raised to an acceptable standard.
If I was a parent & couldn't afford to send my kids to a private school in Australia I'd educate them overseas.