The prime minister’s announcement of an extra $4.6bn in funding over the next decade for private schools makes no sense.

But there is nothing new in that. To engage in the schools funding policy arena in this country requires the ability to suspend disbelief. For this is a sphere in which nothing is what it seems.

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Scott Morrison’s reference to “needs-based” funding to justify this latest special deal is not an accurate description of the commonwealth’s funding scheme for private schools, which is now a perverse derivative of the original Gonski model.

Even when schools have no “need” for public funding to augment the revenue they collect in fees from parents, even where these fees make them inaccessible for most families and add up to well beyond the schools resource standard that is integral to the scheme, they nevertheless have public funding pressed upon them. This funding scheme is better described as “entitlement-based augmented by need”.

It is also nonsense for Morrison or his new education minister, Dan Tehan, to claim that they can guarantee their new billions will make private schools more accessible to parents in the name of “choice”. They appear not to understand that it is not the subsidy that determines a child’s access to these schools, but the upfront fee determined privately by the school.

But, when it comes to schools funding, it’s business as usual to go on recycling old nonsense.

Claiming that subsidies will keep fees down is a furphy if recent history is any guide. The same claim was made in 1999 by David Kemp, then education minister in the Howard government. Despite both Kemp and John Howard claiming that increased public funding would be used by non-government schools to keep their fees down, their fees continued to increase in real terms along with their public funding.

The prime minister has caved in to special pleading from elements within the private schools sector

Between 2000 and 2015, while per student expenditure from governments on Catholic schools almost doubled, these schools increased their own private fees by over twice the rate of inflation.

This was not surprising, since Coalition policy removed the downward pressure on fees that had been built into the Labor policy it replaced, on the grounds that this was a “disincentive to private effort”. “Private effort” largely consists in fees. But when funding private schools, our governments are able to pursue contradictory policies if they feel the political need to do so. No wonder that the Australian National Audit Office affirmed in 2009 that, under the Howard government, there was little or no attempt at accountability against its goal of broadening access to low-income families or even to gather the relevant data.

From an economist’s viewpoint, combining public subsidies with unregulated and uncapped private fees is simply a recipe for blowing out the costs of a service.

Far from using their generous public funding from government to lower fees, all the evidence suggests that private schools have instead used it to enable the diversion of more of the revenue they collect from parent fees towards spending on buildings, grounds and facilities.

The stated rationale for the public funding of these schools by the commonwealth is to ensure that, in combination with their private funding, all schools operate at an agreed schools resource standard, appropriate to the educational needs of the students they enrol. Schools are not permitted to divert their public recurrent funding directly into capital purposes. But, if they instead divert more of their private funding, the policy effect is the same.

Catholic authorities have claimed that their schools are experiencing an enrolment downturn due to rising fees. Is there any credible evidence of research on or by Catholic systems to back this claim? Has the PM sought or received such evidence?

Despite their professions of concern about parents being excluded from choosing their schools, there has been no concerted demand from non-government schools for public funding to be provided at a level sufficient to enable the abolition of fees. This is understandable. The right to charge fees provides a means by which non-government school authorities exercise control over their student intake.

From an international standpoint, this is a rare arrangement. Public assistance on the scale available to most non-government schools in Australia has been accompanied in most countries by a requirement that such schools forgo the right to charge private fees.

As for Morrison’s claims about making private schools affordable for parents, he would have to outlaw fees completely to achieve this for all parents.

His proclaimed “freedom of choice” is limited by what schools decide to charge and what parents can afford to pay privately. And poor Catholic families cannot “choose” high-fee independent Catholic schools in this will-o’-the-wisp world he attempts to evoke.

The PM’s announcement on extra school funding coincided in the daily press with publicity photos of him driving trucks. With his special deals for private schools, he has created even more drive-through holes in a scheme for those who share his love of this activity, while driving his own truck over the public schools that serve the majority of students and that are open to all.

The prime minister has caved in to special pleading from elements within the private schools sector. He and the Coalition government he heads have wiped their hands of responsibility for ensuring that public schools achieve the schools resource standards they have set in legislation, while guaranteeing that these standards will be met by the commonwealth for private schools. States are responsible for the nation’s public schools, he claims. There is no educational or constitutional basis for this claim.

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Over the coming decade, while private schools are enjoying their $4.6bn windfall, state and territory budgets will be under immense pressure to meet the costs of essential services, including for hospitals and healthcare, transport and infrastructure generally. Public schools will be facing demographic pressures as well as the costs of catering for the majority of those students most needing intensive teaching support to gain the full benefits of their schooling.

Several decades of special funding deals for private schools and the expansion of that sector have been accompanied by a decline in aspects of our educational performance, judged by national as well as international indicators. Surely there is a case here for a royal commission? Or, perhaps, a revival of the former Schools Commission? It is no coincidence that the era of “special deals” began with the demise of an independent national agency to advise and consult on school funding.

Transparency and independent analysis are essential to informed and rational debate about and schools funding and are now sadly lacking.

• Lyndsay Connors AO was a member of the former Schools Commission and chaired the Schools Council of the National Board of Employment, Education and Training that succeeded it