It roughly lines up with morning shifts, I guess? When I was working at a grocery store our morning shift was like 6-3 with an hour lunch. I don't know how you make sure your kids actually go to school if you're at work by 6, though... And if you work evenings (or overnights, for places that are still open 24 hours) it doesn't help at all.
I hate how getting up early is somehow perceived to be more efficient.
There's nothing natural about working hours anyway. We could choose to place them when it fits more people.