>Depends on what you call decent. I mean for the cow it might have more space to walk around and eat grass.
Basically, yes. I can see how opinions would differ, that human exploitation makes it wrong. I do see farming involving raising animals for milk & meat as decent if done decently. It's a big question, and imo, fundamental in that it doesn't have deeper reasons.
Singer (you mentioned above) is famously utilitarian (in the bentham sense). So he does go one deeper. Right & wrong = pleasure and pain. For cows specifically, the question gets too weird to do the utilitarian math... for me.
In some senses, cows wouldn't have exist separately from farming, and for the most part won't. They did in the aurochs sense, but auroch are extinct and were probably pretty different. Would the world be better without cows...
Anyway, a lot of this relates to where I live. Visit Ireland, you will encounter cows. Decent farming is more than viable. I'm not even sure feedlots is what you would get in an unregulated market. All agg markets are subsidized & regulated, so who knows. It's even possible to do pork and poultry well, though here it generally isn't.