Not OP but it seemed unambiguous to me given "countries that have adopted". The countries that proclaimed themselves communist at some point -- the Soviet Union, China, Yugoslavia, Cuba, Czechoslovakia, Angola, etc. (Most no longer exist, only Cuba, Vietnam, China and Laos are governed by self-described communist parties today.)
And a lot of those countries had standard of living sharply rise during communist era. People really, really under appreciate how bad conditions were in many of those countries for those who weren't creme de la creme of society, or how much for example interwar Poland history is kept silent about the squalor and poverty of huge portion of the society.
Yes, for various reasons economic systems in many of them failed (or in few cases, it was nationalistic strife that dealt the blow), but others learnt lessons from it (for example, about badly defining and strictly adhering to plans, or too high concentration in one company, etc.)
What about countries that only adopted two “communist ideas”? What if a country adopted hundreds of them, but didn't call itself communist? What if No True Communist Society does XYZ thing that all of the countries on your list have done?
You can't talk effectively about something until everybody agrees on what the words mean.