A better explanation is that congressmen are in the favor-granting business. The greater the growth of government control over businesses, property and employment, the greater is the value of being able to influence Congress. Rent-seeking refers to the use of government as a means to acquire greater wealth by gaining monopoly power or income transfers. U.S. automakers and their unions get Congress to enact quotas and tariffs on foreign imports. Dairymen and sugar producers seek import restrictions on dairy products and sugar.
Labor unions seek minimum-wage laws and other legislation that eliminates competition.
When Congress grants these favors, the recipients see increased profits and wages that come at the expense of other Americans. Using Congress is one way to restrict competition. Using mob violence a la Al Capone is another. For example, if Archer Daniels Midland's CEO Dwayne Andreas used goons and violence to stop people from buying sugar from Caribbean producers so he could sell more corn syrup, he'd wind up in jail. If he makes big campaign contributions, he gets the same result, without risking imprisonment.