That's because in the USA the penalties are still comparatively harsh and a lot of prisons (when it comes to general population) are still quite rough.

Compared to the USA, the judicial system in for instance Canada and Western Europe is a joke. You get seven years and you're out in two.

Furthermore prison life over here isn't all that dangerous. We don't have gangs like they do in the USA. Over here where I live most are locked up due to some sort of connection with organized crime. Most of it is ethnicity-based: Sicilians, Calabrians, Turks, Kurds, Albanians, Moroccans, Dutch travellers, Armenians, Georgians, Chechens, Russians, Assyrians, Israelis, Serbs, Greeks, members of outlaw motorcycle groups or just Belgian white collar criminals... but there's nothing like the "racial tension" that exists in US prisons. Most of those guys here are locked up for serious stuff; in the US you see gang members getting locked up for years and years just because they were caught selling a few nickel bags, over here they get locked up because they were connected to tons.
These are definitely serious guys who did kill people outside prison, but in prison they're not going to shank you. If you keep your head down and respectfully interact with others, you're going to be fine.

Anybody would still take freedom over prison and there are still rats over here as well, but there do seem to be way less than in the USA. I mean, why would you rat over here? If you're someone with serious connections you'll be back in business in a year or two when you get out and your life is rarely in danger in prison.