School districts start at various times, but a primary reason many start classes early is to optimize costs. In particular, districts often start schools early so that buses can run routes with one age group and then complete an additional route for another age group.
Having the same set of buses run multiple routes is generally more cost-effective than having separate buses for every school route in a large district. Early start times and multiple routes allow the district to hire fewer drivers and to own and maintain a smaller fleet of buses. The motive of starting schools earlier for bus efficiency goes back to the 1950s and 1960s in the United States.
Parents often prefer earlier school start times for a few key reasons. For students that participate in extracurricular activities, a relatively early start time allows them to participate in those activities and still get home at a decent time. Some students also work part-time jobs after school. In some cases, families even rely on the student's income for living costs. Late school starts would push back a student's ability to start a work shift at a reasonable time after school. Earlier starts also appeal to parents who want to see their kids off to school before heading to work.