There were and are workers’ unions in communist countries. They didn’t always have their worker’ best interests in mind. Often they were a tool of the communist state to control workers. In addition sometimes you had student movements pitted against workers’ unions and so on.
Exploitation or at the minimum the potential for it exists in every economic system. It’s not a feature exclusive to capitalism as much as people dream it to be so. Even in a barter economy, can I not take advantage of another worker? Of course I can!
I never said that we should install Soviet socialism/state-capitalism, it's not a good system.
Workers unions in socialist countries were basically illegal, there was only one legally allowed union pretty much. In the Soviet Union the role of labour unions were mostly for the state to resolve interpersonal problems, and in theory to allow the state to receive feedback from employees to optimize production, but not in practice due to dysfunctions because of the broken political and economic framework.
Exploitation or at the minimum the potential for it exists in every economic system. It’s not a feature exclusive to capitalism as much as people dream it to be so. Even in a barter economy, can I not take advantage of another worker? Of course I can!