Suzy Khimm notes that private prisons tend to overestimate their savings prior to securing a contract, only to make problematic cuts later, using Arizona as an example:
In fact, the reason that Arizona is taking a second look at its private prisons right now is because of a high-profile fugitive case: Three inmates escaped from a private facility last month and are believed to be responsible for two murders during their flight, having only been captured last Thursday. This is just the latest episode in a long history of scandals that have plagued private prison operators, including charges of prisoner abuse in adult and juvenile facilities.
I don't think there's anything inherently wrong with privately run prisons, but if they can't even save taxpayers money -- and create greater security risks in an effort to deliver as promised -- then lawmakers should think again before resorting to them. Having poured millions into lobbying lawmakers, the private prison industry has also sold itself to local communities by promising to create jobs in the places where new facilities are built. The thing is, if the same funds were put toward constructing new publicly run facilities, the money could have a similarly stimulative effect on local economies -- and could end up delivering more on the dollar than their private counterparts.
The way to save money on prisons isn't to give contracts to private companies that will lowball costs and cut corners, it's to be less punitive, more willing to consider alternatives to incarceration like geriatric release and outpatient imprisonment, and to adopt anti-recidivism measures that actually work. In other words, the way to save money on corrections is to have fewer people in prison.
This is not to say efforts by some states to cut costs haven't led to some terrible outcomes, but the additional problem with bringing the private sector into the matter is that you now have commercial entities invested in pushing the government toward being more punitive, because otherwise they can't make profits. The fewer people in prison, the less money there is to be made in making prisons to put people in.