I would have agreed with this statement perhaps 30 years ago, but I no longer believe that it is true. At least, it is clearly not true that corrections are constantly moving toward treating prisoners more humanely.
For part of our history, this statement would have been true. American corrections were originally not very humane at all. We started with “corrections” that were heavy on corporal punishments like whippings and being put in the stocks. From there, we moved towards less harsh punishments. We moved toward systems that were meant to rehabilitate prisoners rather than trying to simply treat them harshly. This represented a movement towards greater humaneness in the treatment of the incarcerated.
In recent decades, however, the idea of treating prisoners humanely seems to have lost traction. We are much more attuned to the idea of punishing people for committing crimes. We feel like any attempts to rehabilitate prisoners are tantamount to coddling them. We think nothing of allowing prisons to become places where inmates are routinely subjected to sexual abuse. We have abandoned the idea of moving towards greater humaneness in our corrections.