Some atates like FL argue its because the kids at the school bus stop would be standing in the dark waiting for their buses. Particulary the middle school age and younger. Safety issue. I get it. I dont agree thouh.
Middle schooler here in N tx got killed last year crossing the street to the school in the dark.
Not a fault of the darkness or the kid, but the driver involved and the lack of street lighting and/or a crossing guard at the school.