Well a psychologist typically would want to be alone with a patient because the parent could be the source of the problem.
But I cant think of a reason why a pediatrician would need to be alone with the child. That should send up a red flag, and it did apparently with some parents according to the article.
I would NEVER leave my daughter alone with a man. Not a doctor, not a dentist. The parents need to get a clue. But that doesn’t excuse this monster. There must be a special place in hell for people who hurt children.
Then Dr's need a small room with a see-through mirror.