> I dunno if there's much difference between cow milk, soy milk, oat milk
Well given the fact that cow milk exists in nature, has been drank by humans for thousands of years, and the other two are trying to be like cow milk, right off the bat, I think a good working hypothesis is that cow milk is less processed than soy and oat milk. They may pasteurize and homogenize it and add some vitamins, but it is fundamentally pretty close to what came out of the cow. Soy mil and oat milk, need a lot more processing to turn soy and oats into something at resembles milk.
