The US has a pluralistic system of government, where interest groups represent the interests of the people directly to the legislators. Under the iron law of oligarchy, the leaders and organizers of these interest groups have the most influence, simply because they are the most active in petitioning the government. This system helps to ensure that no overbearing absolute majority comes to power that will put its interest above the rights of the people. It is one of the functioning components of democracy, it is not and oligarchy, which is rule by a pre-selected group. If you are defining democracy as a system where everybody just comes together to vote on the issues, then let me remind you that that leads to dictatorship, as the ones who are best able to manipulate public emotions (demagogues) come to power (think "Hitler").

I'm also surprised that anyone on the left would criticize the US for being morally corrupt.

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"It is extremely difficult for our contemporaries to conceive of the conditions of free banking because they take government interference with banking for granted and as necessary"

-- Ludwig von Mises