Most of the possible consequences of sex have alternative actions to support them besides telling the other kid's parents. Someone gets an STI? Take them to a clinic. Helping them get treated is going to be a lot more effective than telling their parents. And most teens who are about to be parents are going to bite the bullet and tell their parents but could use a supportive adult in the room/waiting in the car while they do--or else they have really good reasons not to want to tell them.