Human nature is something you can not change, that's the big problem. If everybody gets paid the same, everybody will have the urge to get paid more by doing more, or to laze around, which logically should make them earn less. The result is capitalism. There's no way to avoid that.

Also, about Lady Floydian's point concerning dictatorships: She's partly right, but mixes causality and correlation. Communism doesn't require dictatorship, and many European countries have democratic parties that promote communism. The reason why all communist systems to date had dictators, was because they weren't voted for; they took power in those countries through wars and revolutions, then enforced their rules onto the people. If a country's voters decide that communism is a good idea, then it's perfectly possible for it to happen without dictatorship.