Against this analysis, however, is the empirical fact that plenty of people did work hard and take risks under Communism - the Soviet space program is one obvio

Against this analysis, however, is the empirical fact that plenty of people did work hard and take risks under Communism - the Soviet space program is one obvious example. It seems that in practice, a reward does not need to be an economic return in order to be an incentive. There are other kinds of rewards: eg awards, prizes, or honours. Most militaries use rewards of this kind.