Because the protectionist EU single market and trade policy is a joke, in one word Mercosur. I see today that after 20 years of jaw jaw still not getting ratified any time soon. Supposedly the benefits to EU businesses are in the region of 4bn euro a year, that's 80bn in unnecessary costs over 20 years to the struggling EU economy, their customers and citizens in the time they have been talking. What a farce.
French Agriculture Minister Didier Guillaume warned the Macron government would not ratify the free-trade agreement “in its current form”.
https://www.express.co.uk/news/world...sur-trade-deal
I'll wager right now the UK implements a free trade deal with Mercosur after brexit before the EU ever does...