That's a fair read, but no surprise. It's a simple formula, really:
money => lobbyists => political influence => gain
On the local level, its corrupt people in power who require a little inducement; on the national level, it's corruption on a massive scale, although none dare call it that, and those who are "bought" demand perpetual payment. They rarely stay bought.
Reform is impossible; those who benefit from the corruption make the laws, interpret the laws, and enforce the laws. Not even a massive voter revolt would have lasting effect. Throwing new bodies into a cesspit produces nothing but more corrupted bodies.
In the US, the primary vehicle of corruption is partisan politics, which demands total party allegiance and retention of power, denigrating the needs of the nation.
The root cause that fuels the vehicle of corruption is human nature: personal ambition, avarice, lust for power, and fear of retribution, to name a few.
The example of Richard Nixon and events leading to his resignation to escape certain impeachment are noteworthy only in the fact that he was so immersed in the game that he forgot one basic tenet of US politics: you're supposed to hide it all. Nixon came to assume that everyone had accepted how the game was played. He was incredulous at hearing the panoply of moralists decrying his administration's political tactics. After all, a clever President worships at the altar of deniability: Nixon forgot that. He was perhaps the last of the truly honest Presidents. When he said, "I am not a crook!" he truly believed it. He just meant that all high-level politicians are bent, malleable SOB's that point into any favorable wind, regardless of the direction.