Some districts have high school start early, so that they can work in the afternoon. They also have to stagger school start times for the bus schedule to work. Without enough drivers, the bus has to pick up and drop off HS students and then go pick up other students.
I can understand the homework, as there has been some research suggesting that it isn’t as beneficial as we believe.
There would need to be a different schedule for students in many school activities, like sports, music, and theater among others that need some before or after school practice.