Meat is hugely inefficient, but Americans demand it. If you told Americans in a crisis, "For food security reasons you're all limited to a quarter pounder per day", we'd have a national riot. They're used to three times that.

They'd insist that they'd die without enough protein, and vegetable protein sources don't count. Even limiting their meat to a half-pound per day would cause riots, even though that is more than enough protein.

So efficiency just isn't on the table here. We're going to over-support our meat industry.