Communism is an extreme form of socialism, in practice ALWAYS totalitarian. .
Oh that ain't true. Any kind of gummint or social philosophy can be taken to the extreme of totalitarianism but that's got nothing to do with the philosophy itself, unless the philosophy is nothing more than power-hungry dictatorship.
There's a religious sect called the Hutterites (Hutterian Bretheren) settled in western Canada, the Dakotas and Montana. They run their colonies under a near-totally communist system; no private property, all work and assets belong to the collective, etc. But at the same time they are the antithesis of authoritarian, with a Minister and elected Council heading the operation and votes on community decisions. A communistic democracy.
Communism and authoritarianism are like fish and bicycles: unrelated to each other. We tend to look at historical examples of the USSR or Cuba and confuse the underlying social philosophy with the way they went about implementing it, but they're two different things.
You're right about that. True communism is described as being class-less, state-less, and money-less. Without a state there would be no authoritarianism. I suppose you could look at it as a form of money-less anarchy.
The reason communism is regarded as being totalitarian is because there's absolutely no way to implement it without having an oppressive, authoritarian state to enforce "equality" and "collectivism."
Of course there is. I just gave an example in the quote above. Trust me, there's nothing oppressive or authoritarian about that sect. In almost five hundred years living this way they have had I think one murder and two suicides. It doesn't need to be "enforced" because the people believe in it. And because they're entirely self-sufficient and disengaged from the affairs of the countries, provinces and states they live in, it can be considered a "state" in and of itself.