It’s well exemplified in the phenomenon of regulatory capture, where the dominant companies in some industry write the very regulations that govern them. They do so in such a way as to diminish the threat from new competitors and thus maintain above-market profits… for a while. (In the long tun, they grow complacent and lose to more dynamic industries.)
In this understanding, a congressman is a feudal lord who maintains his fiefs, and the companies who finance his (reelection) campaigns are his vassals receiving government privileges in return. The American economic system is not laissez-faire capitalism!