Just to add to the other answer, which stresses that French farmers are just as productive, the reason EU farmers and their US farmer counterparts get subsidies

Just to add to the other answer, which stresses that French farmers are just as productive, the reason EU farmers and their US farmer counterparts get subsidies is geostrategic: if for some reason you end up at war with your food partners, the last thing you want is a starving population. If, overnight, farmers need to start producing twice as much, you want to make sure that it's a possibility. (And yes, it's also soft power when dealing with developing countries.)