there's probably a good argument to not allow random cameras in

you're right. there's also an awful lot of very obvious good arguments for allowing recording and public access to recording, such as the incident where a prisoner was locked in a scalding shower until he was so badly burned that his skin "fell off at the touch" (https://en.wikipedia.org/wiki/Killing_of_Darren_Rainey). Like so many incidents of its kind, there was absolutely no hard evidence available to prove what happened and it ended up being yet another case where someone died horrifically and officially no one was found to have done anything wrong but several million dollars did change hands. If prison guards are torturing prisoners to death and getting away with it, the argument that they don't need surveillance needs to be a whole lot better than "probably good".