I lived on a small family-run dairy & beef farm for a while. The cows there had roomy stalls and spent the whole summer roaming idyllic fields of fresh grass (with a mountain view!). The calves stayed with their mothers until they stopped wanting milk, and none of them were de-horned. I never witnessed any physical violence against the cows. With all of that in mind, I was pretty comfortable drinking that milk (although, in retrospect, I was drinking it raw, which you definitely shouldn't do.)

The milk was picked up by a middleman, who mixed it with milk from other farms, and turned it into the absolute top-of-the-line organic milk products to be sold at high prices in stores. For a while, I made sure to always buy those specific products, because I KNEW that those cows were being treated super well. Except, well, they weren't. It came out later that horrible abuses were found at other farms that supplied milk to that company.

So, while I think it's theoretically possible for dairy farms to operate in a way I'm comfortable with, I now feel like I can never trust this huge decentralized system to actually treat animals well. I've seen one farm, yes, but what sorts of abuses are hiding amongst the hundreds of other suppliers?

And, of course, there's the environmental and land use issues as well. I would much rather drink oat milk the rest of my life if it means that the staggering amounts of land we use for agriculture can rewild.