Cultural differences. The US has far too many cultures, immigrants (we are a 100% immigrant nation after all), etc for it to work here. Norway and Sweden are VERY culturally homogenous and also VERY anti-immigrant.
Of note, Sweden just elected people of an anti-immigrant, anti-muslim party to their parliament in the past national election. That should give you an idea.
While Moore is... well, I think we all know not to take him seriously.
But... the US doesn't have to be what it is.
We COULD close borders. Then instill community service for most non-violent offenders. We could legalize pot.
Also, maybe get rid of some of the 20,000+ federal laws (plus state and county), so that less than 100% of the population commits crimes (as is the current situation within the US)
With the money saved from excessive imprisonment, we could improve the correctional element of the correctional facilities (which right now are only used as 'punishment' places)
Hell, in 50+ years if we did the RIGHT decisions, we could be like Norway in terms of crime, prisoner populations, and prisoner rehabilitation.
Of course, that won't happen.
Oh and to those harking about prisoners over there not getting punished, you are confused about how the justice system works. In the west, and most first world countries, prison is used to CORRECT people, not punish. The is why they are called correctional facilities. If you really want punishment, instill corporal punishment. Which, I tend to agree on for violent criminals. I'd personally prefer to lose a finger than lose a year of my life.
But don't mix the concepts. It is the hypocrisy of America that always fucks things up. We decide to make 'correctional' facilities with the idea of not pushing yet correcting, and then we punish and don't correct.