At 16 years old a young person has the right to walk out of their home and never have any contact with their parents again. If their parents reported them as missing and the police were to find out where the young person was staying, the police would be strictly prohibited from revealing their whereabouts to their parents.
College lecturers have no way of knowing which of their students are still dependent on their parents, or who has decided never to have any contact with their parents again (or, of course, who falls into a 'semi-independent' category in between). It follows that they must adopt a common policy and respect the privacy of all of their students. Failure to do so would, at least, be a serious breach of professional conduct; it might also be a breach of data protection legislation.
Chris