There is no evidence that soft prisons work better. Prison is a deterrent.

And Jan 6 was an insurrection, the Covid vaccines are safe and effective, and a man can turn into a woman by putting on a dress and makeup.

There is a ton of evidence from Finland that "soft" (your word, not mine) prisons work better. They switched over from the harsh, punitive, Russian-style prison system that emphasised punishment and didn't even know the word "rehabilitation" to a more enlightened, rehabilitation-based system in the 1970s, and never looked back. Recidivism rates dropped enormously, prison costs fell, and crime rates fell.

The majority of prisoners in Finland are kept in low-security open prisons, including murderers considered to be at low risk of reoffending.

In Norway, recidivism rates fell from 60-70% (typical for punitive-style prisons) to just 20% after introducing a similar system.

In terms of deterrent, there is plenty of evidence that the threat of punishment is not an effective deterrent. What really deters people is the consideration that they will be caught. People who think they won't be caught are not deterred by the threat of punishment, no matter how harsh. (Well duh.)

There is a ton of research which shows that imprisonment has, at best, no effect on the rate of re-offending and often results in increased recidivism. Imprisonment for some crimes may be necessary for the safety of the community, but it's not going to rehabilitate criminals or deter people from committing crimes, and it often pushes people into a cycle of crime and prison.

Harsher prison sentences don't deter crimes. If they did, the jails of 18th century Britain, or of Tzarist and Soviet Russia, would have been empty.

Most crimes are not carefully thought-out, rational calculations that balance the potential gain versus the potential punishment. The average crackhead is not making rational calculations about cost and benefit before committing a robbery. The average 20 y.o. tradie, drunk as a skunk on Friday night at a nightclub with his mates, doesn't carefully weigh up the satisfaction of walloping that bloke who gave him cheek versus time in prison for assault and battery before getting into a punch-up. Nearly all murders are spur of the moment things committed in the grip of strong emotions, not the result of rational calculation that might be deterred by harsh punishment.