They have to work to survive, but are not condemned there for life, and are being compensated for their labor. The dragons are more taking reformative measures to help them adapt to their new world, Unfortunately farm work is pretty much all they are qualified to do for now. Released, a while ago. https://wordrain69.com/manga/white-cat/extra-2/ They clearly know they can eventually leave They have no skills to survive in that world, the dragons gave them a chance to develop a skill set that would let them survive. And it is clearly not life imprisonment form their perspective, seeing as the lackeys are talking about saving up funds to leave.