It's a bit depressing to me that we've known this for at least twenty years, and possibly more and it's still a problem.
A major concern has been busing. Even in normal times, districts use the same buses and drivers for students of all ages. They stagger start times to do that, with high schoolers arriving and leaving school earliest in the day. The idea is that they can handle being alone in the dark at a bus stop more readily than smaller children, and it also lets them get home first to help take care of younger siblings after school.
If high schools started as late as middle and elementary schools, that would likely mean strain on transportation resources. O'Connell said Nashville's limited mass transit compounds the problem.
"That is one of the biggest issues to resolve," he said.
This is basically it, school systems not wanting to buy the extra buses or hire the extra drivers they'd need.
Unfortunately I don't see this ever being solved without a major cultural/financial shift in the USA towards properly funding education. Too much financial pressure to have fewer buses and fewer drivers. If my high school and middle school had started at the same time as the elementary, that'd be like 14 new buses alone at $60k-$110k a pop, not including driver wages and the diesel for each one...and we had more than one high school and middle school in our district. So it'd be more like 50 new buses, just to start HS and middle school at the same time as elementary. The cost would eat smaller districts alive. It'd be several million just to procure the buses new.
It's baffling how many U.S problems can be traced back to car-oriented development.
Here in Sweden, dedicated school buses are uncommon - getting to school is usually a matter of walking when young, and then using the common public transportation when older, or biking, or a mix of those two.
Here's how I got to school while growing up:
Years 1 -6: school 0.4 km away, walked or biked
Years 7-9: school 2 km away, biked or took the bus
Years 10-12: school 9.1 km away, took the bus to school
Note that this was one of the most car-oriented cities in Sweden of about 100k people, meaning that this experience is probably unusually bad for Sweden.
I won’t argue that the US is exceedingly car-focused, but that’s partly because distances travelled are greater. When I was a kid, my elementary school was 2.6 miles (4.18 km) from my house, and many classmates would have been even further. I had classmates who had a 45 minute bus ride (time stretched by making multiple stops obviously). While I’m sure 5 year olds can bike 2.6 miles, it’s probably not ideal and certainly not ideal in snow/sub-zero (Fahrenheit) temps. Much of the US is just very spread out.
When I was at school, the bus was a charter from the company that ran the local public bus fleet. Every other time it was running public routes or just part of that companies reserve.
But this was in the UK, where dedicated school buses are exceptional.
In the school district that I live in (and where my kids attend school), elementary school starts earliest and middle/high school both start at roughly the same time.
I've found that this works really well since my youngest wakes up and is ready to go earliest anyways, I don't have to adjust my schedule because they're out of the house before I have to get to work and I would need after school care regardless. My older kids can more or less fend for themselves before school so I don't need to worry about them while I get to work before they leave.
If elementary school started at 9 like high school and middle school I'd have to organize care for my youngest both before and after school since I'd be working at both times.
And now imagine if instead of making new schools in places where everybody needs to be driven there either by car or by bus we build them so the majority would walk or bike as it is the more convient option. Other countries like Japan can imagine. Turns out it's actually better to walk/bike to school even who knew!
The problem is you'd have to build not just schools, but entire neighborhoods so they are walkable + tunnels under any larger roads between them, or maybe guarded crossings would do here and there.
While it could certainly be done, the majority of the US is built to be car centric from the ground up.