It’s the same as people putting water in milk in the past
Water is still put in the milk, aside from i being economical it’s also because drinking milk from cow directly could give you diarrhea and taste is too much form many people. I’ve seen the process on bio farm with manual milking.
Fun fact: if you stop drinking milk for a while you are very likely to develop a lactose intolerance
Interesting. Does it work for all “races” . Because I thought Caucasian developed high rate of lactose tolerance genetically to compensate for lack of vitamin D from sun light among other things but e.g. Asians have higher rate of lactose intolerance.