Social Issue: Sugar Ethenol

The sugar cane farmers of this contry are worried because in the next year there is oging to be a large influx in sugar imports from Mexico. They view ethenol made from sugar as a way to save the industry. Brazil has been making sugar ethenol for nearly 20 years, but according to the artcile in the Times, sugar prices are too high in the US for us to do the same. There are also high tariffs imposed on ethenol from Brazil.
I'm not sure why we're importing so much sugar from Mexico (something to do with NAFTA, maybe?) I don't understand why we need to import some good that we produce. Ok, maybe we don't produce enough, but why don't we import just what we need. We shouldn't be eating that much sugar anyways. And ok, say we do have a surplus, why don't we use it to make fuel? Or use it to expand on ethenol technology?
If Brazil has been making fuel from sugar since the 1980's, why haven't we? Or if not from sugar, then something else?
Why don't we do things in this country that make sense? Did I miss that Social Studies lesson or something? Maybe they should get rid of Social Studies and teach Forethought.