Earlier quoted context omitted.
Not to get off topic (but to support your point), I once read an op-ed that made an argument that the increase in obesity (in the USA) was due to farm subsidies. That is, cheap corn is used to make high-fructose corn syrup, and that low cost sweetener in turn ends up in everything. And of course, as you mentioned, grains make cows, pigs, etc. cheaper. Again, not ideal for the human body and even less so for Mother Na…
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.
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.).