@JGoldman10,
Probably because they are white, and it's more like they are paying thousands of dollars to adopt a white child than to NOT adopt a black child.
I doubt that there are very many black couples paying thousands of dollars to adopt white children.
I'm an adoptive parent and my adopted son is white and now 29 years old. 29 years ago, it wasn't necessary to spend any money to adopt any child - unless you already adopted one American child and so had to go to a foreign country for a second or third.
The County Adoption Agency had us review about 10 three inch binders of photos of older children, minority babies, and babies who were sick or disabled before we finished the paperwork.
The pictures were heart-breaking, but we didn't have any children and knew the first would be huge challenge whether or not it was adopted. We weren't about to makes the odds tougher by adopting a child that required the skills of experienced parents.
Our goal was to add a baby to our lives, not rescue anyone. That might be perceived as a selfish goal, but I don't think it was.
Perhaps if we adopted a second child we might have considered a special needs child, but two years after my son came to us, my wife got pregnant,and two years after that she got pregnant again.
If there are more black babies who need adoptive parents than there are couples who want to adopt them, the situation is a lot more complex than a simplistic charge of racism can explain.