Why can’t people sell their children?

What if there was a system that allows for people to find the right homes for babies , where you can get paid .. Like why is adoption such an expensive hard process. Yet we can breed puppies and sell them to someone who can take care of it. But instead the government takes ur kid away for free . I had a Friend severely abused in an organized foster care trafficking thing. The world is corrupt. Why do we cry about how bad the systems are yet we continue to allow it . For what reason . Instead they put the babies to foster care systems where they get abused. I have known several people who as babies Their adoption process was turned down, due to stupid complications . and they were put into the system. Good healthy kids , .