Canada

I think this is the key thing to remember about those that commit crimes. The penalty is never in their minds when they're considering committing a crime. Either they're presuming that they'll get away scott-free, or that the alternative of not committing the crime is worse than any penalty that could come.

Find me a single person who debates if they'll get two years or five for doing something. Most criminals are completely unaware of what the penalties are in the first place. It could be life for anything worse than shoplifting, and they'll still do it because the penalty was never in their minds in the first place. This is why putting the entire burden of crime prevention on punishments don't work.

Not saying that punishments don't work, but they don't prevent serious crimes in the first place, only minor ones. Punishments only deal with criminals by preventing them from having any opportunities to commit crimes because they're in jail. It's having people be in a good enough position in life that the prospect of ANY jail time enough of a detriment to avoid committing the crime. Having too much to lose is a far better way to prevent crime than guarantee the destruction of a life when you're already destroying their life via other means.

Either way, people who commit violent crimes are never thinking about the punishment before doing so. It's only those that do minor ones like speeding that think about it. Though that said, if you get jail time for speeding, maybe people would actually stop doing 80 in a 40 school zone.