North Korea is ruled by the Supreme People’s Assembly (최고인민회의) which is directly elected.
Cuba… Why couldn’t they’ve use machinery imported from the Soviet Union to develop their agriculture and fishery?
No reason not to. Lots of Soviet farm machinery there.
I can give a longer response when I’m not on mobile, but so I know where to start: what have you read? What sources have you read about China’s economy, for instance?