Oversight. Legal adoptions, surrogacy, and even embryo donations all have at least some level of regulatory oversight and required legal procedures to protect everyone involved.
Without such oversight, those who take the kids have no protection from birth parents changing their mind (some states explicitly allow take-back periods, others do not).
It also protects the children. Newsflash: both sexual and labour slavery exists in the US. If you know the right series of people to ask, you can have sex with, abuse, and yes, even kill a child and you don’t even have to go to some third world hellhole to do it. Pretty much every major US city has at least some amount of child sex slavery going on, and let me make this clear: I do not mean 17.5 year olds, I mean CHILDREN. Little kids.
If unregulated selling of children was legal, it’d be that much easier for such horrible places to get their hands on more fodder. You can bet there would even be drugged out mothers renting out their wombs regularly to supply children to such fates. There almost certainly are such people, but right now, it’s at least difficult to do because of legal restrictions on what you can do with your own infant.
