Maybe things are different in different areas of Australia, but where I work I've found two things to be consistently true:
1) Jail makes most people worse (more evil), not better. Yes there are exceptions, so note the use of the word "most".
2) Jail is far from the end of it for even moderate offences.
For both these points most people don't see the evidence. There are an unhappy group of people who are employed or contracted to deal with criminals post jail. What they see is people who will probably never really settle properly into society, they are often damaged before they go into jail, and come out even more damaged. And the fact is they are under a bunch of restrictions once they get out, but have often become paranoid about the system that now controls them in so many ways. The same system places an expectation on parole officers, counsellors, and psychologists, that they will deliver sufficient care and management of these damaged and difficult people. Such people try as best they can, with limited resources, to do their job. They deal with monsters, in part they loathe them more than you ever will, but also they know the awful secret, that most of the evil people are more created than born.
Why does the justice system seem to get things wrong so often? I don't call it a justice system, it is a legal system. The system is subject to principles. For example, the death penalty was abolished because too often it was discovered after the fact that the executed person was actually innocent. If society doesn't want any system or individuals that it invests with authority to be tyrannical, than in-principle you can't have the judicial authority being responsible for killing more innocent people than any of the criminals it is supposed to be dealing with. There are plenty of other principles in play, like the balance between societies demands for retribution (such as this case), and societies desire for rehabilitation (which is expressed by at least some people in most cases, but more on that in a moment). Unfortunately systems are not all that good at considering individual cases, even though the judiciary is supposed to be set up to allow judges to consider the individual cases, the reality is they are tied down by system level considerations such as principle and precedent. What a lot of people also don't realise is just how politicised the judiciary actually is.
Something else that isn't well understood (blame the media if you want, but I think the reasons are more complicated) is that time and time again the offenders that are put through the corrections system were themselves victims as kids, this is where, when the facts are known, most people do start to lean towards trying to rehabilitate. Consider for a moment what you would do if you had to pass judgement on someone who has a heroin addiction and the evidence shows clearly that they were repeatedly raped as a 7 year old girl and have since developed paranoid delusions, PTSD, and dissociative disorder. Her addiction to drugs happened because she doesn't get any support (she is unsurprisingly scared and distrusting of people so didn't make any good friends when growing up, and social support systems are grossly underfunded), and shooting up provides short term relief from some of the daily things she struggles with, memories, nightmares, intrusive thoughts, etc. You are the judge. Do you send her to jail, where you know she definitely won't get support, and she will absolutely be subject to more trauma?
I don't make this up as a hypothetical example, I have a colleague who was attacked by a person who was so effected and was suffering an episode of paranoid psychosis. What most people don't see is the reality on the ground of trying to deal with these people and being subject to the principles and ethics of a society that is conflicted and which makes demands for the judiciary to do things to others (retribution) that they would demand not be done to themselves because of the context and because of what has been done to them (they want rehabilitation to be considered for themselves).
It is easy to be judgmental on such awful cases as the brutal killing of children. Maybe it helps us deal with the awful knowledge that someone out there did something so terrible, maybe it makes us feel self-righteous. I suspect one thing it does is it helps us believe that society isn't what is wrong, it is individual people out there who are evil.
Maybe we just don't want to face the facts, we live in a society that is in many ways broken and twisted, and which doesn't have effective answers to serious problems. Evil gives birth to more evil, the percentage of people subject to the corrections system who were innocent victims when they were children is far higher than the percentage in the general population.
It is a lot easier to point the finger at evil people, than to reflect on the evidence that we exist in a society that has culpability in the creation of evil people. For many of us society feels like it has been good, has given us opportunities that we've seized and made something out of. Could it be true that the same society is simultaneously complicit in bad things happening to other people? That would mean that the same systems that were good for us, were hurting others. That is a very difficult thought. Much easier to say individuals are to blame, and to demand they get locked up and feel our wrath, albeit indirectly, we don't actually want to meet any of these people.
