The poorest eat the least meat, lentils, chickpeas, beans and rice are cheaper everywhere. Ask me how I know.

This is a classic question of intuition. Personally I see your argument as a cop-out. By definition the supermarkets are just selling us what we want. That's what supermarkets do, they're not charities. If you want (somewhat) cruelty-free meat, it's available in the organic shop across the road and it costs four times as much. Suddenly you don't care so much about the chickens, right? Not blaming you or anyone in particular. This is who we are as humans. We want it tasty, we want it cheap, and the rest is something of an abstraction.