Rather than throwing billions at expensive corn ethanol, we could easily import cheap Brazilian ethanol, if the idea was to reduce oil imports. It's not. The idea is to buy votes.
It may not stay "cheap" if we buy all of their output.
As someone on the thread has pointed out, alcohol import duties make it too expensive. So I agree we could "easily" do it if that difficulty were removed. Still, I think US technology has a key role to play.
Also, you're too pessimistic. to say that this is all about buying votes. There is a real problem. Volatility in the oil market is hurtful because it is so fundamental. This volatility is going to become worse with China and India becoming so much more developed. There is a legitimate role for government in this.
Finally, economic efficiency, while very, very important, cannot be our only criterion. We are funding governments whose interests are inimical to us. Iran is using oil proceeds to develop nuclear weapons. If an application of US techology to the energy sector could render oil unimportant, that is worth some subsidy.