Here is brief assortment of things you aren’t supposed to know. The terms under which Circle Healthcare was contracted to take over an NHS hospital in November 2011. The date by which the NuGen joint venture was due to construct a new nuclear power station at Sellafield. How much the Lord Mayor of Chester spends on leasing a chauffeur-driven Bentley.

This isn't an exhaustive list, you understand: these are just a few of the incidences in which that will-sapping phrase "commercial confidentiality" has popped up in the news over the last few months – put there, no doubt, by journalists steaming from the ears at their inability to get hold of actual facts and figures.

This dreaded phrase comes from the Freedom of Information (FOI) Act, which makes clear that, while the public has a perfect right to know about most of what the government does, there are certain areas in which the powers that be are within their rights to keep schtum: anything, in fact, deemed “prejudicial to the commercial interests” of somebody or other.

The result of all this is that there is a vast range of stuff involving taxpayers’ money that taxpayers aren’t actually allowed to know. Want to see the un-redacted contracts under which outsourcing firms are running public buildings? Or what targets they have to hit, to claim their rather expansive bonuses? Tough. None of your business. Bugger off.

If the private sector feels at all concerned about the impression this is leaving, it’s hiding it well. In early September, the main business lobbying organisation, the CBI, put out a report calling for greater transparency regarding how services were performing. This, it argued, would make it easier both to spread good practice, and to highlight when things were going wrong.

The reason for this sudden commitment to openness is simple: it drives trust. The more information we have about how good private firms are at offering public services, the CBI thinks, the more comfortable we’ll all get with the idea. The report doesn't quite come out and say it, but it seems to be aimed at things like the Staffordshire hospital scandal; its subtext can best be summarised as 'Game on'.

Not everyone’s going to agree with that, of course, but most people, at least, would probably say this commitment to openness is to the lobby group’s credit. There is, however, a gaping hole in its argument: it only talks about one side of the equation. The report includes an airy promise that “citizens are entitled to know how taxpayers’ money is spent”; but it mentions commercial confidentiality only once, and that’s to say how important it is that the rules allowing secrecy stays in place. As far as the business lobby is concerned, we’re allowed to see what’s coming out of public services; we’re not allowed to see what’s going into them.

If pushed on the matter, the CBI’s wonks point out that financial arrangements within the public sector tend towards the opaque, too. And they argue that publishing contracts would stifle innovation. Commercial confidentiality works like a patent: no one’s going to spend money coming up with a cleverer way of doing things if they think their rivals will instantly nick it.

But even if every closed contract is hiding a wealth of innovation, which is frankly hard to believe, isn't it in our interests that their rivals can see this and start copying it? If the risk of financial transparency is that everything gets cheaper, then I'm not convinced the downside is quite as big as the CBI thinks.

The real reason commercial confidentiality persists lies elsewhere. Outsourcing firms may not want any pesky members of the Public Accounts Committee trawling through their contracts – but neither does the government. There are no clear rules setting out what can be classed as confidential, or when it can be overruled by public interest. There is, what’s more, plenty of anecdotal evidence to suggest that specific financial information sometimes stays hidden at official request. If you were the guy who signed the PFI contract that included a £300 fee every time a light-bulb needed changing, you’d want it hushed up, too.

But there’s a sort of Prisoner’s Dilemma at work here. Both outsourcing firms and public authorities think it in their short term interest to keep everything quiet – but both might benefit from a touch of transparency. If there was a public interest rule that meant any contract involving public money would be subject to FOI, then the government would probably benefit by getting products and services cheaper. But companies could benefit too: partly because they could see what their rivals were up to, but mostly because everything the CBI says about the value of trust is entirely true.

Fairly or otherwise, a lot of people remain convinced that outsourcing companies are all evil profiteers, growing rich off the backs of children or sick people. Some of them aren’t. Some genuinely believe they can provide better public services at lower cost. Were they to be more willing to prove it, we might start to believe them.