If you think prisons have morality think again.
Why would we send anybody there then, unless that person was guaranteed never to emerge?
They often have cruder morality, but oh yes they have morality. The question is only what morality they have. And that’s going to be sent back out into the world in virtually all cases, in some manner or form.
And Scandinavia of the past is proof that in some circumstances it is viable to have prisons that to us would seem impossibly soft. The old point of the Christian reformers was to make them places of penitence, not of warping.
I think you are using the fallacy of all-or-nothing. The goal should always be as much of a part as we can reasonably muster.