First try to understand why cannibalism is abhorrent, malum in se, and rather than just abnormal.

If you find yourself justifying cannibalism you'll be able to justify buying babies like IKEA furniture.

But the truth is that children from surrogacy tend to feel that their surrogate parent exploited their real mothers. These feelings are gaslit, and in extreme circumstances the surrogate parents cut off the children the way they would never have been cut off by real parents.

Bottom line is that people literally cannot be owned or bought, and if you try to buy a child you're only renting the experience of parenthood, not the real thing, hence those relationships are emotionally easier to sever from both sides.

Renting or buying a person's labour is not exploitation if the person is getting better at something, increasing their own capacity rather than draining it.