Basically, thought experiment: imagine a population where everyone starts with a fixed N dollars. Random-walk each dollar a few iterations and you end up with a bell curve of money distribution. Now start again and instead of random-walking them, apply a probabilistic walk, where having more dollars makes you a proportionately more likely recipient. You end up with a skewed distribution with a few rich controlling most of the resources. Now imagine being a congress-critter in that skewed world. Who are you going to have to cut deals with? And you can make the rich-get-richer rule steeper now, because the dollar-owners are cutting deals to make dollar-taking easier. And now your wealth distribution looks like the real world.

The answer is simply that money itself, the alienable control of resources, is the cause. In a society organized by money, corruption and misrule will result. Any "symptom control" amounts to pumping the distribution flatter - it's a sisyphean task, structurally opposed to the power that money creates, and hence metastable at best.