The Soviet Union and China are/were not and have virtually never been socialist countries - they are/were state capitalist economies.
Socialism means "corporations are owned by the people working in them", as in co-ops. State-owned corporations under brutal dictatorships are in no conceivable way "worker-owned". They all called themselves socialist just as they called themselves democratic - as in, basic propaganda.
This is very relevant in a discussion of left-wing VS right-wing economies. The Soviet Union and China are firmly in the right wing in reality, just as much as Nazi Germany or Fascist Italy were. They just had different propaganda.
A small note: state owned companies under actual Democratic societies is a more complex topic on the left-wing VS right-wing debate, that I won't go into here.