This was also a thing in Ireland. The school building opened at 7:30am, but it was basically just the principal and janitor in that early. As one of the kids getting dropped off relatively early (7:45am), I just did my homework in the school building until classes started at 9:15am, which meant my evenings were free.
There was no need to force all the other students to start earlier too. (And I would then nap in first period as a result of getting up early, which teachers would take in different ways. Some just left me, some would try catch me out by asking questions, but since I had just done the homework an hour before and read ahead on the material, usually I could answer)
I get it for kids younger than 8-10 (depending on the kid), but after that age kids should be able to get out of the house and to school on their own. For the youngest it can be solved with a before school program. The kids just need a place to eat breakfast and chill with their friends before the school day starts.
Letting a child under 18 step outside without being in a car or under direct parent supervision is child abuse in the US and the police will usually be called.
No, there are countless shocking cases of police showing up for things like a child was playing in the front yard unattended while the parent was inside and in some cases the child was taken from the parent due to this “abuse”.
Allowing a 13 year old to walk to a bus stop would be extremely high risk for having police called.
It absolutely happens often enough all across the coutnry to be a serious concern for parents, and you can find plenty of news articles about it with some simple web searches.
I see kids wandering around my neighborhood by themself or in groups all the time, and where I grew up(rural CA), I roamed 5-15 miles away from home regularly on a bike or 4-wheeler.
Early start times in the US long predate both the large growth and suburbs and the shift from almost all kids having a stay at home Mom to having both parents employed outside the home.
A ridiculous justification, of course, but that's what you get with a combination of helicopter parenting and a society overreliant on cars.