First of all, you have to realise the idea of imprisoning someone for a crime is very old paradigm indeed.
You also have to realise, we have people heavily influenced by ideology on either side. A lot of people on the right want their pound of flesh, they want maximum and harsh punishment. A lot of people on the left want sentences alternative to prison but a lot of these people end up fucking up again anyway. It's clear to get the best way, we have to put all that aside, look at the evidence and be pragmatic.
One of the fundamental aims of imprisonment is to "rehabilitate" individuals who have committed crimes.
This raises the question, are prisoners actually rehabilitated by the duration of their sentence?
Rehabilitation can and will only be effective if the individual being imprisoned is willing to be rehabilitated.
Whats the alternative though? Send them back out there with no attempt at helping them? Surely, they're likely to slide back into crime just because of no other option. Only some criminals commit crime because they expressively want to. It's quite clear poverty, low SES (socio-economic-status), coming from an abusive family background or mental illness are strongly correlated with criminality. You don't see a whole bunch of rich kids, from a good home, forming gangs and shooting up cops.
I'd also argue a fair few criminals also have a mental disorder of one variety or another.
It's clearly better than doing absolutely nothing. They dont necessarily need to want to be rehabilitated, just like kids who hate school still pick up things along the way.
Anyway, the focus isn't on repeat offenders, hardened criminals. We know that rehabilitation probably won't work for these people anyway. The focus is on first time offenders and young people in particular. We can probably save a few of these people before they enter a viscous cycle.
Having been to Barwon Prison in 2011, I met four criminals who were all sentenced to 20+ years in prison. All four of them had served prior sentences.
After speaking to them all in great detail and asking a multitude of questions, all of them said that they would certainly be back in prison again. This was especially disheartening, considering a man charged with drug trafficking, drug possession and murder was charged with drug trafficking shortly after turning 18. He served a sentence, got out of prison, and was back in within 4 months. Now he's in there for another 20-something years.
A rich kid from a well off family like you goes to prison and you suddenly understand whats wrong with all these people?

I know people who have gotten stabbed, robbed, hit across the face with guns and other innumerably sick things. It's not nearly as simple as you think it is.
Also, considering the recidivism rates and where they stand, it doesn't look like imprisonment is an effective way of rehabilitating people.
You know nothing of crime unless you've had to live with it. Pop down to footscray or sunshine some time and you might realise why some of these people are criminals. The poverty in these areas is pretty bad. A lot of people come from broken, abusive homes. Even from my own school i know people like that.
Just to sweeten the crime they could commit after getting out of prison, many criminals admit to "networking" in prison, and learning how to commit the "perfect crime".
Learn that from watching cops?
You have to go deeper and think why they're networking. Partially its due to gangs and gang culture, partially its because they got no other hope on the outside. You get out of prison and its orders of magnitudes harder to get any kind of decent job. Thankfully, its not nearly as bad here as the USA. We have decent levels of employment and we don't chuck people in a hole for 30 years for petty crime, no wonder they resent society and build up criminal networks.
No doubt some people will do this but the idea is to give them hope on the outside so they can actually try be functioning members of society.
I think that the high recidivism rates and prisons' failure to effectively rehabilitate people can be attributed to this opportunity to network and communicate freely with other prisoners.
To quote the Australian institute of criminology:
"About 60 per cent of those in custody in Australia have been imprisoned before. Reoffending behaviour or recidivism can be influenced by many factors including poor education and employment histories, mental illness and bad physical health, as well as drug and alcohol misuse.
An AIC study into reducing recidivism through vocational education and training examines the impact of education on reoffending behaviour. It looks at the results of a Queensland vocational education and training program that show an offender’s chance of returning to prison after two years was 32 per cent for non-participants in the program compared with 23 per cent for participants. To find out more about this subject, explore the AIC and other related research this website." - http://www.aic.gov.au/crime_community/communitycrime/recidivism.aspxOR..you know...maybe its the fact they're in prison..surrounded by criminals in the first place. Undeniably, dangerous offenders deserve to be in prison but by sending minor criminals to prison, you're turning them into hardened criminals. You're associating them with much worse criminals and crushing a lot of their future prospects. I think we should have alternative sentencing for some crimes rather than prison. This would address part of your issue.
Perhaps prisons should be changed in that each prisoner should have their own cell, own bathroom, own allocated time in a smaller outdoor area etc. They should not be able to speak with let a lone be in physical contact with other prisoners.
Well for one, that would be loads more expensive. Two, it seems unnecessarily cruel. We are social creatures, lack of contact is pretty bad. I doubt everyone deserves this equally. Does the triple murderer deserve it as much as say the car thief? It lacks a principal of fairness and proportionality here. It also stinks of retributive justice and just causing as much pain as possible, which clearly won't solve anything. Anyway, sure, they won't be able to communicate with other criminals in prison but so what? If they really wanted to, they can do that once they get out. Even in solitary, you see prisoners shouting between cells and passing messages. They will find a way, trust me.
Not to mention the probable psychological damage and other problems that would occur. I might make them even more violent/dellusional/damaged towards the guards instead.
I believe, that a model along these lines being implemented would see a dramatic decrease in the recidivism rates as prisoners would be rehabilitated much better.
I honestly fail to see even a shred of logic behind your idea that sticking them in the hole will successfully rehabilitate them.
There should be an interview that they need to pass in front of a board, demonstrating that they have been rehabilitated.
People lie and this is all far too objective. Keeping people in prisons for even longer won't do them much good, not to mention the massive cost.
Solve the real root of crime and you're already half way there.