You wouldn't be able to do that and still be a respected member of the international establishment. Long term isolation is rightly almost universally condemned.You are getting far too complicated again. If the prisoner is isolated and confined to a whitewashed cell measuring 2m x 2m and remains there 24 hours per day, they can’t commit crime.
There's also inconvenient matters like showers, meals, haircuts and medical treatment to be taken care of, so large numbers of prisoners would need inordinate numbers of prison wardens to individually attend to those, even more costly than our present system.
And wardens are corruptible, how do you think many of the phones and drugs get in?
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