Actually, in typical totalitarian societies, drug dealers usually make arrangements with the "authorities". The thing is that totalitarian societies care not one bit about the welfare of their citizens, they only keep up appearances. What then happens in addition is that everybody on drugs is known to the authorities and if any of them ever voices a critical thought, they will be publicly crucified. All that are behave like the sheep they are supposed to be are left alone.
So, no, expecting that crime against citizens is less in authoritarian societies is not realistic. The one exception are some theocracies and quasi-theocracies where they are true believers and even see thinking anything else than the church/party line is a capital offense. There you actually may get less crime. The cost is extreme, though.