Why don't we harvest human breast milk and sell that? Seems like it would be much healthier for humans to be drinking milk from their own species. We could make cheese, ice cream, and many other dairy products and they would be better for us.
I pumped human breast milk for a year for my daughter and I have to tell you that it's a big pain. My nipples were so sore at first that I cried.
There are women who express their excess breast milk and donate it to milk banks for babies who are unable to digest formula, but the milk banks pasteurize and sell it and it's very expensive, something like $3 or $4 an ounce. I considered donating since I had an ample supply, but I was afraid that I would not be able to keep up with my daughter's needs since I almost exclusively pumped by then, so we bought a freezer and I froze the excess milk instead.
If you had women sell their expressed milk, I guess that it might have some of the same problems of paying people to sell their blood, in that they might be be less likely to disclose a health condition that should keep them from donating.
You seem to be lost in your own thoughts.