I don't think most people here arguing for a more rehabilitation-based prison system think it works perfectly or even good in the US. But on the other hand the US prison system has more inmates per capita than any other, so clearly something in either the legal system or the prison system has gone wrong.
Reform is needed, and IMO more punishment and less opportunity after exit will probably not help.
Advocating for shorter prison sentences is not the same thing as wanting to change the philosophical underpinning of the justice system to rehabilitation instead of retribution. I think a lot of people are confusing the two.
I do think some of the sentencing in the US is too high. But also that people deserve punishment for their crimes.
Reform is needed, and IMO more punishment and less opportunity after exit will probably not help.