For a state that does not grow corn and is oil rich, I simply don't get the logic at all.
EPA regulations per The Clean Air Act. Large metropolitan areas cannot meet the EPA limits on emissions. These areas, called "non-attainment" areas, are forced to use cleaner burning fuels to reduce emissions. That fuel is E10 and is required by the EPA in all non-attainment areas. This is why you typically find non-ethanol gasoline in rural areas, only.