The purist form of true communism is voluntary and is practiced in the Catholic faith by various groups of Priests and Nuns. The operative word is voluntary, and even at that level there are still human problems. Liberals want to "force" the "high ideals" of the communistic view of the world, i.e. share and share alike [with them being the more equals in charge of distribution}.
This is the rational of the zero sum game. In a fantasy dream, a utopia, an alice in wonderland, this might work, in the world of humans, it doesn't stand a snowball's chance in hades.