Why reform the prisons when they're working so well?

At Whitzerland, a discussion of privatized prisons based on a report by the Bureau of Justice Assistance:

The basic pros and cons of the argument are simple:

Pros Private Prisons: 1. provide construction as needed in order to reduce government debt. 2. produce facilities in half the time it takes the government. 3. provide economic devlopment. 4. create competition that lowers costs

Cons Private Prisons: 1. may become monopoly in the system through ingratiation, favortism. 2. have financial motivation that is opposite the end goal (i.e. production is the machine so they want to keep the parts working-inmates) 3. procurement is slow, inefficient and open to risk

That sounds like an argument for privatization to me, since all the cons (yes, even #2) are potential problems even in our current system.

Whatever. Whether privatizing prisons works or not, what I don't hear addressed in Whit's post is the question of purpose. So what if private prisons are slightly more efficient than public ones? The issue should be what private prisons are producing. Right now prison is really more like a criminal internship and/or rape-fest. That just doesn't seem to line up with my Christian vision of what internment should be about, namely, rehabilitation. Whit, what does that BJA have to say about that?