>Authoritarianism is fundamentally right wing.
Go look at a political compass. Authoritarianism is when you use force to push your ideals, whether they be radical/liberal (left) or orthodox/conservative)(right) ideals on a populace with extreme authority. Communism is considered left/radical, if you use government force to make people adopt it, that's using authority, hence authoritarianism. Please learn definitions and political axis before making silly arguments.
China isn't really communist because they tried it and people starved, then they had to go back to capitalism or some degree of it, but kept the authoritarianism, and effectively became some hybrid version that leans fascist.
Communism simply never works at scale, socialism can to an extent, assuming its not abused and there's a homogeneous society with shared cultural values and purpose that includes to contribute and to not abuse it. Hence Nordic socialism, which of course breaks down when you bring in those that don't share those values as its doing now. I've heard enough Swedes bitch about Eastern European migrants abusing their social welfare to say nothing of now to see the idealism fall apart when self interested parties without the same cultural values enter en masse.
Human psychology being about protecting and serving the interests of your tribe and things like "Dunbar's number" and the limit of the number of people you can literally care about and prioritize makes it impossible at scale. Families can be communist, even a small group of 10-50 people (more or less a cult or small tribe), massive populations can not. They simply are not going to work for the benefit of others without receiving something in exchange, unless you use a gun to their head, which is why all communist regimes start out authoritarian, but holding a gun to someone's head for 10-50 years won't change 200k years of evolutionary programming. Hence why Marx is good at pointing out capitalism's flaws, but he's naive and even more fundamentally flawed when it comes to prescribing a solution that does way more harm in the end.
Truth is most successful societies adopt a hybrid solution, socialism at the community or local level where everyone works for a shared purpose and contributes to the local community, whether that be through a church, small local government, etc. with capitalism that allows trade and mutually beneficial deals to happen with those outside of that community.