Do we? Last time I checked we put people in cells for committing crimes. What sorts of prisoners are you talking about here? It's not obvious to me but perhaps I'm being thick.
No, we put people in cells because they represent a threat to the general public. Of course, it doesn't always play out that way in reality, but their are a limited number of options re punishment as well.
Society has a right to protect itself. If your decisions put my life, as well as thousands of others, in danger unnecessarily then you represent a significant risk.
