Does Child Protective Services really insist teachers not consult parents on issues of neglect?

Well, teachers are mandatory reporters when they suspect abuse or neglect and for the child's safety they don't make it policy to call potentially abusive parents to let them know they are suspicious- this could result in more harm coming to a child and the parent keeping them from school. It may be a pain in the for you, but it's for the child's safety, I'm sure you can sympathize with that. Provide your side of the case and if there were any witnesses that could say that she hadn't been sick that morning and move on with your life.