In an ideal world, teenagers would not be engaging in risky sexual activity and would not be catching sexually transmitted infections (STIs). But we do not live in an ideal world. And young people are often dumb. The best we can hope for is that when some young people make bad decisions, these will not result in dire or lifelong consequences.
If, say, some 16-year-old has unprotected sex and catches chlamydia, we should hope that the teen will get treated—even if that means telling a parent what is going on. But, is this likely? Given an option between telling a parent they're sexually active and simply shutting up and hoping for the best, it doesn't seem unreasonable to worry that teens may choose the latter.
That's why it's probably a good idea not to condition STI treatment on parental consent. You risk stopping young people from seeking testing and treatment in the first place.
