The idea is that teenagers find it really hard to go to bed early. But school still starts very early. So they end up sleeping less than they should to function. The anti biology stance of "they should go to bed earlier" is not helpful. What's helpful is starting school later, let them have their vigil time into later hours, then they can sleep and recover fully, and do better at school. Thus potentially creating better educated adults.

I’m pretty sure teenagers are naturally programmed to go to bed at later times.