Actually I don't know if we are disagreeing. I don't say U.S. agriculture is unproductive - just that it could be as or more productive without gulping such huge amounts of fossil fuel or using such overwhelming amounts of poison. And that the techniques for doing so are mature, well known, and not more expensive (even in the narrow market sense) than conventional industrial agriculture - that in fact they are a form of industrial agriculture.
I also think it importantt that we not overrate the success of U.S. agriculture. It is highly productive, but NOT the worlds most productive. Certainly not in yield per acre, and I suspect not in yield per person hour either. Many EU nations have higher labor costs than the U.S.; it would be surprising if the high wage EU nations use agricultural labor less efficiently than the U.S. does. Since I provide some statistics on yield per acre,, does someone else want to return the favor with yield per person hour?