No mechanism is capable of greed. Actually, capitalism discourages true greed. A truly greedy person lacks the respect for money and property that a successful capitalist learns. To strive for security, for the well being of one's family, even for some degree of power in this uncertain world is not to exhibit greed. If you are looking for a greedy man, try prison.
Democracy is another system that is unjustly impugned.
In fact, it is so perfect that it seems the Fathers of our country did think of everything. They even left us the freedom to abstain from voting, if we are observant and humble enough to realize that we don't each always know how to make every single decision. By auctioning themselves off and making thoughtless decisions, the voters show that it is in their hearts that prejudice, greed, cowardice, and envy reside. Although it almost goes without saying that lawyers are the problem, it is still said that the jury system should be reformed. If the jury system was genuinely practiced, we would find that it is actually faultless.