u?
EDIT: note this is not so much about npc being thrown in jail but more so there presence in jail form the start of the game.
jails in oblivion where kinda sad. no one in the whole of cyrodiil commiting any crimes. you were usually one of the only ones in there.
i think prisons should be more dense and more around. imagine breaking into a jail the prisoners could either welcome you and convince u to free them or starts riotingg and raging.