My family took care of a small herd of dairy goats when I was growing up. They could definitely make their displeasure known if you tried to make them do something they didn't want to (especially when they were very nearly your own weight). Milking time? Most days they were perfectly happy to jump up on the stand for us to relieve their udders for them, sometimes even before we'd gotten everything set up.
I am careful where I get my milk from because the big dairy institutions are rather problematic. And I agree that the broad disempowerment and incarceration inherent in farming is an issue on its own. But saying that milk is always, unequivocally, unwanted theft (and respectively that farms provide an unqualified worse life) is just the other side of the same human-exceptionalism coin -- you're removing their agency to say "yes".
