But why does US farmer wanting to export to EU don't just enforce EU norms on food production ? Do not use hormones or forbidden pesticides in the EU, enforce traceability of all all inputs. Then they could negotiate easily with EU for their products, checked by EU validated organisations, to enter the EU market. I often think that it's not for the some free market ideology but just to force other countries (like EU) to abandon any normative sovereignty.

I understand that a global agricultural market with a single norm would be better for mercantile exchanges, but for the single producer EU (or China, or whatever) is a sufficiently big market to be targeted exclusively if they want. OMC should not conflate normative barriers with tariff barriers, they have a real purpose (maybe USA is wrong to eat so much pesticides).