Reading that article, it seems that the mom was arrested because the cops wanted to. Someone called the cops for a child walking down the highway by themselves, and then the cops showed up and arrested her. Cops can arrest people for any reason practically, a lot of times because they just don't like you. I was thrown up against the back of a patrol car and searched when ordering chinese food late at night once. I don't see that she was charged by the prosecutor, or that the child was taken away.
The other link you have is neighbors that obviously dislike each other, and they told the cops the kid was in danger.