Some non-government school advocates will say "we pay taxes - we have the right to have government money spent on the education of our child in a different system". But let’s look at that more closely:
The majority of non-government schools are in the old category 9 -12 system which include the Catholic system which educates 20% of students. They receive, on average, about the same amount (95%) as public schools, but in some cases their funding has continued to increase under the government formula so that they now receive more funding than public schools. Clearly the government is not saving any money on funding private schools such as these.
The My School website data also shows that public schools received less government funding for capital works on average than private schools. Adding that funding to the private sources of income for private schools means that Catholic schools were able to spend more than double what government schools did on capital works while independent school spent more than triple. Again, hardly a saving of government funds!
Recent Federal funding to new non-government schools is often an inefficient use of scarce education resources as these schools are set up in close proximity to existing government schools which could easily provide for the children's education. No assessment is now done of the possible effect of new schools on neighbouring schools, nor any assessment of the demand for the new schools which are frequently very small.
In addition all non-government schools are dependent on public money in far more ways than are publicly admitted or accounted for. The wealthy schools which cater for about 10% of children, absorb a large share of the money available in our society for expenditure on education, in the interest of a minority. Aside from annual per capita grants and capital grants from State and Federal Governments which have increased enormously in recent years (particularly to the wealthier non-government schools):
every dollar raised in school building appeals is tax deductible, so that in addition to contributions from the individuals who benefit, every taxpayer carries some of the burden of extending the facilities of these schools they are exempt from some land taxes (and never paid payroll tax) the travel requirements of their students are a cost to transport budgets (guess who’s paying for those school buses ferrying private students?) they have free access to many Education Department facilities whose costs are accounted to the government's own system
On another economic note, parents’ fees to schools, particularly the high fee-paying schools, go into supporting the spread of the private organization running the school, by purchasing large country properties in the case of most of the ‘elite’ private schools. If this funding was instead spent by the parents at the private schools on other goods and services in our society it would in fact improve our general economy far more than paying high fees to a few private companies.
Finally, international studies have shown the value of a well-educated population: Education substantially increases the earning power of an individual over their lifetime, which contributes to the earning power of the society as a whole. Our children are our greatest asset for the future, and ALL of them deserve a high-quality education, not just those whose parents can afford to buy them one.