I think bribery could still work in Netherworld prisons, if you assume that while Daimons might not care about money, the human guards they employ might. Unless the idea (and I admittedly am clueless on this issue) is that the Daimons themselves are always doing the guarding. Including the feeding and letter sending and stuff, which seems a bit off: "I'm a fiendish otherworldly demonic beast... here's your supper!" And I like the idea that not everyone who works for or supports the Netherworld is a Daimon. But again I have no idea what the intent or reality of the situation is, being a newcomer to the island myself.
No, the idea is that the Netherworld prison isn't really much like the other prisons. As a thought, you would probably be put into some kind of cage and shoved off towards the soulforges.
