What do you think is the great danger there? Remember, they don’t have internet.
Even my ancient Kindle can access the Internet, if there’s WiFi; and there is probably a way to do that in some prisons.
I think that reading - and books, newspapers, magazines available to convicts - are important. But if you wanted to offer something digital, you’d have to be careful...
Many people in prison aren’t going to be there forever. Whatever you can do to cultivate and lift their minds and spirits might make a big difference in how well they do when they leave prison.
Unless they are specially-made tablets that do not have a WiFi chip, they have the capability to be connected to the Internet. And specially-made tablets would cost on the order of tens of thousands of dollars each (they'd have to be specially designed and manufactured -- and with these extra costs only being divided among a small number of tablets, the costs would be extreme. Think $30,000 hammer)
If they use retail tablets, then mischief can ensue pretty quickly. Remember that prisoners have a LOT of time. And remember that, while most of them are dumb as a box of rocks, some are pretty smart...and would be able to exchange those smarts for quite a bit of value.
"JPay will get money from transactions that happen via the tablets (ebooks, music, videos)."
Convicts already extort other convicts for commissary and packages. Could be a possibility of extortion...forcing an inmate to purchase items they don't really want. All the extortionist would have to do is take the tablet to watch or listen to the products the other inmate was forced to purchase, then return the tablet to the extorted con when he's done. And it would happen over and over. Having worked 25 years in that prison system, it wouldn't surprise me if that happened.
Smuggled cell phone = mobile hot spot.