And yes, I'm pretty much aware of current industrial farming processes and what that does to the environment, but maybe you're missing the forest from the trees, as in maybe it's industrial farming that we should get rid of. Plants and animals are basically engines storing and converting the sun's energy into nutrients and natural ecosystems are very much sustainable. Add fossil fuels in the equation, like what the industrial age did and you get the current clusterfuck. Our grandparents seemed to have no problem in raising their own livestock with sustainable practices. Surely we can do better than them, since we live in the information age and all that.
And for people worried about efficiency, cost and over-population, we are wasting about one third of the food we produce right now. And we spend much less of our income and time on acquiring food. There is room for taking a step back in terms of throughput and maybe focus on quality rather than quantity. Which might be a good idea given that even though the calories in our food is at an all times high, for the first time in history we're seeing overweight children suffering from malnutrition.
The real problem I'm having with your argument, as it's what vegans usually say, is that if you want cheap, you can't beat a combination of corn and soy grown through an industrial process, as these are the most efficient farmed plants we have. Whereas many fruits are very inefficient, consume a lot of water and are not sustainable at scale. Just saying, if you want efficiency, start eating corn.
In short, it is because an animal will always eat more food to be food, than would be needed to just feed people on plants directly.
> maybe it's industrial farming that we should get rid of
"Free-range" farming practices are even more damaging and unsustainable than confined breeding operations, for the simple reason it takes more land and more resources.
> Plants and animals are basically engines storing and converting the sun's energy into nutrients and natural ecosystems are very much sustainable.
Not quite, plants are the nutrient producers - they synthesize solar energy into every amino acid essential to animals, into phytonutrients, etc. Animals, on the other hand, are nutrient consumers. I.e., animal derived foods are only nutritious because the animals ate plants.
> calories in our food is at an all times high
That's mostly from animal products and refined, packaged foods.
> Whereas many fruits are very inefficient, consume a lot of water and are not sustainable at scale
This is simply conjecture. Are you absolutely sure growing fruit is inefficient compared to modern animal agriculture?
> start eating corn.
Gladly. Starchy vegetables - complex carbohydrates - are the foods our ancestors ate for many years; they are regarded as a diet staple of several ancient societies.
EDIT: And as mentioned elsewhere: government subsidies in many countries (and/or import/export controls).
There is increasing pressure to lower farming subsides in most of the world in part because food costs have already fallen so much. 1935 1/lb chicken $5.07 (inflation adj), 2011 1lb chicken: $1.34 But, also from a wide range of more politically charged issues.
Removing those subsidies would not affect only meat.