However, this letter doesn't talk about the other side of the issue- girls being coerced into abortions by their older lovers, or by others who want the baby dead. At least parents, even those who would demand their daughter have an abortion upon notification, would almost always have their child's (at least perceived) best interest at heart. A parent is likely to know their child's medical history that would avoid any complications. A parent would be more likely to listen to their daughter if she changes her mind at the clinic. A parent would want an abortion done as safely as possible, even if it cost more money. A parent would be their for their daughter if she need therapy. A parent can step in and work to end the underlying problem that caused the pregnancy in the first place.
A teenage boy or older predator won't do those things. A nurse or other non-related adult does'nt know the children. There is no foolproof solution that covers 100% of life's scenarios, but when it comes to the welfare of children, I am willing to bet on the parents 95%+ of the time.