To my understanding, cow's milk is not exclusively a "lactation" milk (mother's milk). It has been a staple of ancient cultures/tribes and is still used by tribes all over the world, not simply modernized/civilized cultures.
This one misunderstanding that cow's milk is fit for lactation only is a flawed/invalid reference point for modern research.
Cows don't give milk only for a certain amount of time after giving birth. It is not "lactation"/weaning milk.