That’s the start time for all schools, not high schools. The public high school data is here and shows Massachusetts is indeed second earliest at 7:38am.

r/confidentlyincorrect

As someone else said, we're talking about high schools, not all public schools K-12. The reason this is focused on high schoolers is that teenagers have a natural shift in their circadian rhythm. Kindergarteners are not teenagers and that's why OP didn't include elementary schools. The discussion around shifting to later start times is mostly focused on high schools and in some cases middle schools.