There is also a national security issue to make sure a nation can feed itself. The government's responsibility is towards long term sustainable food supply for it's citizens.
Still, subsidies given do not really indicate long-term sustainable food supply. The most efficient way to guarantee food for the population is by growing plants directly.
If it turns out that the farmer that uses the water for his grain fed factory-farm animals, then the allocation of that money was useless.
There's much more protein/carbs/fiber calories per energy wasted in vegetables than it is in meat in the case of factory farmed meat.
To me it just looks as if luxury foods like meat have large industry players that have influenced the law and the politicians to get subsidies they need to keep their products as cheap as ordinary poor-man food (potatoes, beans, dark greens etc.).
