I think I can add a little here.
I am not going to comment on the Libertarian philosophy, mainly because this is a US centric message board and my take on it would be out of the correct context.
But,
What about privately run prisons - Well in the UK, we have a small number of them, we had one run by some outfit called Wackenhut at a prison called HMP Coldingley. It seems they were not making enough money, so they simply walked from a fully populated prison and left the place locked up behind them!!!
Nope, not making that up, the state had to step in on the very same day and take over - not an easy thing to do considering all the daily functions such as feeding that have to be pre-planned.
All prisons in the UK are inspected, they are given a rating of between 1 to 4, 4 being highest, 1 being lowest.
The idea was to ‘drive standards up’ HAH! DON’T MAKE ME LAUGH!
The aim was to give the government a stick to beat the public sector prisons over the head. The idea was supposed to be compare the standards in one prison to another, and of course its obvious which ones would be better.
Except that every single private prison measures worse than every publicly run prison, to the extent that each and every private prison in in the lowest performing quartile of the rating system
What that actually means is that private prisons perform worse in terms of violence, suicide, rehabilitation, even the prisoners themselves don’t feel safe in private prisons.
As to why, well one must suspect the low staffing levels, and the low wages which attract a certain capability of staff are likely the main culprits. Private prisons tend to cost less to run than the public sector, however the true cost is in the reoffending, which is worse, so the full burden of cost should also include the cost of reoffending, and in such a case, I suggest I is highly likely that private prisons cost more to the public than state run prisons.
Its all about where you measure value for money, is it in running the institution or is it in the total cost to society?