I agree with your view in general, but there is a reason why the agricultural business is heavily, heavily subsidized. Largely for national food security reasons.
If that wasn't the case, I am not sure the US would be a competitive position to grow staples compared with much of the rest of the world, which in itself is a whole topic of discussion.
Given that it already is being subsidized, I think thought needs to be done for handling the topic of broad agricultural good distribution and subsidies. Frankly I think corn, bioethanol, meat etc... should lose their subsidies but that in itself would be quite a vote loser.
E.G. How about canals, barges, railways instead of roadways