Some states will not allow you to use their system unless you are a resident in that state. This isn't a quick and easy process for anybody, no matter who you are. It's going to take some time and requires a little work. Some adoptive parents are very vulnerable to begin with and have ostensibly already gone through a great deal getting to this position in the first place, perhaps having undergone extensive fertility procedures. So when this is something a couple wants complete control over or something they want to happen immediately, they have to realize, unfortunately it is not a quick and painless process.
Birth mothers can change their minds and things can go wrong.
However, working with the right people and going about it in the right way can preclude some of the worst things that could happen, from happening. Couples who are looking to adopt children can prevent mistakes by not cutting corners.