You are a great fan of linking this issue to historical ones that have no bearing, aren't you?
The issue of contraception was (and still is?) bound up with the fact that it is still illegal for children to have sex under the age of 16. The fact that many of them do, and always will, is not the point. The age of consent is set in law to protect them from predatory adults. If a 13 year old tells an adult that she needs contraception, she is, effectively, saying that she is having sex, and as such, breaking the law. By not reporting the matter, the doctor, teacher or other person is colluding in breaking the law, so the situation needed to be cleared up for their protection. People like Victoria Gillick, who felt that parents had a right to know if their daughters were having sex were involved in that discussion, but parental knowledge was not at the root of it.