If prisons are repositories for no-good people, political rhetoric about prisons is a repository for no-good ideas. The opposition uses them in a predictable way, sounding the incompetence klaxon when there's a riot, when reoffending rates are high, or when prisoners escape, but otherwise keeping completely silent. Governments themselves have a more complicated task, demonstrated in its essence by Chris Grayling at the beginning of the week.

He wants to sound tough in the runup to an election – and doesn't want to alienate anybody who could conceivably vote. This leaves him with prisoners and children, and children are a tough target when people feel so sentimental about them. So he puts out a statement about prisoners: they shouldn't be allowed to wear their own clothes, they shouldn't have Sky TV, and they should have to earn privileges by good behaviour, rather than simply gaining them by the avoidance of bad behaviour.

Frances Crook, head of the Howard League for Penal Reform, wrote in the Guardian that the privileges Grayling was mainly talking about – satellite TV, inmates wearing their own clothes – were private prison perks. Having fewer, cheaper, less well-trained staff in private prisons, they used the Sky package as an "opiate", and saved on the prison having to provide uniforms. In the cheapest-per-head prison, prisoners don't even get bedding. They have to buy it from a catalogue provided by the prison, and their families pay. You could write a book about the cycles of impoverishment this creates (quite a short book: it would conclude "this stinks").

Crook generously floated the idea that Grayling was pretending to address prisoners when in fact he was addressing private sector operators, discreetly telling them to pull their socks up. A less diplomatic reading is that he doesn't have a clue what happens, where, or what he could possibly do about it, but just feels like a brawl – a nice safe one, where he's the only one not in handcuffs.

There's a wider point here. If we were just going to note which Tories are the biggest and most incompetent mind-thugs, well, this piece would have to be a lot longer. How is it that privatising prisons – quite high up the Tory agenda – would deliver results that are anathema to a Tory worldview? It is because the private sector, in my view ill-suited to the delivery of most services that are about human relationships, is peculiarly ill-suited to the prison service.

It's partly a question of being insufficiently scrutinised. Neither government nor opposition can get a lot of mileage out of a positive prison story. There's a lot of nuance and counter-intuitiveness – success in reducing reoffending rates will often start off looking like a soft regime, where prisoners spend too much time on cognitive behavioural therapy and not enough time packing nails into boxes. Innovative ideas for rehabilitation might look dangerously like an unofficial surge in noncustodial sentencing. Ideas that should save money (making prisoners work) actually cost money (in supervision – the cheapest thing you can do with a prisoner is to leave him in his cell for 23 hours a day).

When good results don't translate into political capital for anybody, the structures that would normally build up to support them – targets, headlines, a sense of direction permeating beyond the prison service itself – don't materialise. When the Inspectorate of Prisons uses the word "outstanding", it don'tdoesn't mean "great", it means "yet to be done". There's very little organised congratulation and even less public glare. Who would want to look any more closely at an area where good news is bad news, and bad news is only good news if the other guy's in charge?

But sometimes it's doubtful whether even a very engaged political class could make any difference. The dominant providers in the prison sector are global – G4S and Serco, or, like GeoAmey and MTC, operate globally. GeoAmey, incidentally, was running the vans from which the Manchester prisoners escaped yesterday – they were awarded three contracts for "escort and custody services", worth £177m, £178m and £216m, which run until 2018. It is unknown how many escapes would have to occur before those contracts were terminated prematurely. Probably, it's more than two.

These firms are never held to account by government for the way in which they behave in other territories. The scandal of Serco's training manual in Australia, in which staff were given "principles in controlling Resistive Behaviour", and told to use "striking technique" to cause "motor dysfunction", didn't stop our government awarding prison and parole contracts in Britain. This is illogical – any corporate behaviour, anywhere in the world, shows what that company will do for profit when government isn't watching. If you're going to have to remain in a constant state of vigilance just to stop your prisons turning into Guantánamo Bay (run by Geo), you might want to consider whether it would be cheaper to keep them in-house.

Crucially, prisoners represent two different, incompatible propositions to the public sector and the private: they are cheapest for the state when they're successfully rehabilitated and most profitable for the private sector when they're not. This leads to absolutely heinous corruption cases, like the judge in Pennsylvania who was sentenced on Monday for taking kickbacks from prison providers to give juveniles longer sentences. But it also leads to the simple, observable reality that, when the people running the prisons make a profit from the prisoners, prison populations do not go down.

This should be Chris Grayling's big worry. Sky TV packages, headline-grabbing as they may be, are the least of anyone's problems.

Twitter: @zoesqwilliams