Politics, strange bedfellows, etc.
Fast-forward to the present-day and we see the same peculiar collusion between big business and, yes, left-wing environmentalist groups. As Matt Purple writes:
[In the late 1970s] Ethanol was more established overseas, particularly in Brazil which produced ethanol from sugar cane. America could import this fuel for cheaper prices than were available domestically. [Archer Daniels Midland Chairman Dwayne] Andreas knew Jimmy Carter's presidential campaign was in trouble, so he struck a deal. If Congress would slap a tariff on foreign-produced ethanol, Andreas would open a new ethanol plant in Des Moines, boosting Carter's political fortunes in the Midwest. Carter agreed and the tariff was passed.
By then, Congress had caught ethanol fever. Liberal environmentalists talked up gasohol as a step towards cleaner skies. Midwestern politicians from rural states waxed poetically about the American corn farmer. In 1980, the government passed an income tax credit for companies that produced gasohol. The credit would be increased in 1990 and again in 2004.
And so, despite the fact that corn ethanol is actually less "green" than your average gallon of gasoline, American consumers might soon be forced to use even more of it. Read Purple's article in its entirety for all the sleazy details.
Bootlegger, meet Baptist.