> Unfortunately teenager and adult hours are forced to be synchronised,

No, they aren’t. Even with the progressive infantilization of children over the last several decades, its still generally widely accepted that children over 12 can be left alone for a few hours at a time.

Though shifting the standard workweek to 30 hours and adjusting to that by moving the standard start time forward by two hours wouldn’t be a bad idea, either.

It sounds like you're saying that since we can trust teenagers to get themselves home from school at all, it follows that we can also trust teenagers to get themselves to school from home on time. I don't think this logic works for all teenagers, even with a later school start time.

I have been doing this since age 13, so I see no problem assuming decent transportation links to take advantage of.

I think the point is more, teenagers are more motivated to leave school and go home than to leave home and go to school.

That's the teenagers' problem. At the age of 13, it's about time to know that you can hate doing something, and yet still have to do it because it's your responsibility and because you will have problems if you ignore it (just like in adult life).

A lot of people are comfortable with children coming home from school a couple hours before their parents get home. Many of those people are much less comfortable with children waking up and going to school a couple hours after their parents leave for work.

Even if you are right, adults and teenagers still sync around dinner time, they still sync around social activities, etc.