Of course, possession and use of drugs is not a crime in the Netherlands (selling them is illegal for hard drugs and soft drugs above a certain quantity). That

Of course, possession and use of drugs is not a crime in the Netherlands (selling them is illegal for hard drugs and soft drugs above a certain quantity). That explains away part of the difference. If you consider fewer things to be crimes then you have less criminals. Dutch laws are also more tolerant on things like prostitution (if not forced), euthanasia (if properly executed), underage drinking (not in a bar), and a few others. A clear side effect of being in prison is that you are more likely to get the wrong friends and less chance of a job which leads to more crime. Rinse & repeat. That explains away a lot of the rest.