Hello!
Thanks for your suggestion.
Our main focus has initially been police, which over time has changed to Emergency Services. We still have a long way to go, to get there with LFB, Highways etc. Prison service would really bring limited value to the server. It is unlikely that civs would often look forward to playing as locked-up prisoners. In some cases, it is hard to get civs booked in through custody alone. Therefore, I'm afraid we will not be looking at implementing a prison system.
Thanks