But even members of Congress, whose energy is increasingly diverted to fundraising, have long recognized the potentially corrupting effect that big money can have on them. More than 100 years ago they banned corporations from donating directly to federal candidates.Government has power to create monopolies, adjust prices, and tax, and wields considerable other anticompetitive powers. It is in the interests of corporations to bribe politicians to benefit them at the cost of consumers. Framed another way, politicians have a franchise with which they accrue the monopoly rents they create for firms through bribes. If a law creates $10 million for a corporation in excess rent, then a politician should be able to gain up to $10 million in bribes, as firms compete for the rent.
Let us imagine that this legislation prevents future competition and allows firms to gain full monopoly rents in the future, rather than politicians. In such a case, long-lived corporations would be willing to pay the full net present value of monopoly profits today. In other words, we might imagine that short-lived politicians one hundred years ago sold their franchise at the expense, not of consumers, who lose the same amount either way, but of future politicians. The transaction is displayed graphically below (click to enlarge).
Just because politicians banned their future selves from doing something does not mean that they thought it immoral--it can simply be them selling their franchise for donations today.