[p_l]

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.)