you type like using land from semi-deserts isn't destroyed for meat production...
you need to plant, fertilize and apply pesticides to maintain grass! or do you think grass with sometimes 60% of protein per gram grows out of nowhere? or that the global grain production, which more than 85% goes into feeding livestock that it's sometimes 20 times less efficient to produce the same quantity of protein, can't be distributed to the population?
Ranches in Montana and Texas definitely do none of those things. It's native grass, running about 1 cow per acre. Fertilizer and pesticide for an acre would be way more expensive than the profit on 1 cow per acre.