Your first sentence is phrased too extreme :) People who agree about objectives can still have (non-moral) policy arguments. That may be due to a misunderstand

Your first sentence is phrased too extreme :) People who agree about objectives can still have (non-moral) policy arguments. That may be due to a misunderstanding or a lack of knowledge by some of the parties, or simply because society (and hence the economy as part of it) is an extremely complex dynamic system that we only understand in broad strokes. That's when the good kind of economics happens. (Unfortunately, most economics that you see in public is the bad kind perpetuated by "think tanks".)