Prison is an interesting analogy. If you're talking about using commissary items to barter, I agree that's an independent ecosystem. But if you're talking about stuff that comes in from the outside like phones and drugs, then that's completely controlled and sanctioned by the guards and sometimes the Warden, but point taken.
I feel like you're more of a purist when it comes to economics (that's not a slight) and I'm a bit more jaded. I used to be a purist thinking the market dictated the economy and made corrections, etc...then the housing fiasco happened here in Florida. The government picking winners and losers changed my outlook.