Because it’s cheaper for Mc’Donalds and Burger King but probably not for the average consumer. Grocery store beef quality has gone down after Covid except Prime grade and local butchers $$$.
For context, I've known that McDonald's uses rain forest beef since the mid-1980s when my dad first told me about it. I thought they stopped that for a while, but nope:
Nothing has been done to stop it because of a number of cultural problems: 1) Americans love beef: "why would I eat what food eats?" 2) America could stop all conflict around the world, from deforestation to war to civil rights abuses, if that wasn't directly at odds with the appetites of our capitalist empire and 3) scarcity mindset for survival has so dominated the Global South for so long that nature is seen as a resource to be exploited, far below even the dignity of human life, due to unrelenting debt pressure from the IMF to create a wage slave class for harvesting cash crops and labor/resource-intensive commodities like beef.