> "Best" is a combination of... - minimizing cost to the district (number of buses, etc)

No. The paragraph I quoted implies that the parents have some notion of "best" start times that has nothing to do with the district's perspectives. But the article makes no attempt to describe what that is! (Other than what I already mentioned and questioned.)

Child-care, and not having your kids practice football in the dark is the kind of thing that makes sense.

But what does school start time have to do with race and income?