The difference is, everyone admits Nazi and terroists and pedophiles are bad people. You don't seem to admit maffiosi are bad people.
About policemen/politicians/...: if they are doing something illegal, then they must be punished Period.
If those policemen/politicians/...just make a mistake, then so be it. Their intentions are good, and that can't be said about maffiosi.
They just are criminals, and they know it themselves, they wanted this life. Maybe the Yakuza is more bad because they have childporn, that doesn't make the maffiosi less criminal.
You don't have to accept my points of view, and I don't have to accept yours. But nevertheless, the Cosa Nostra is a criminal organisation, and I can't even understand a little bit why you idolize them.
The books you read about them, don't they say what crimes the maffia commits?