If you want to have a bunch of people who typically get ready at 0800 with their children for school at 0830 and work at 0900, it's much easier to adjust what t

If you want to have a bunch of people who typically get ready at 0800 with their children for school at 0830 and work at 0900, it's much easier to adjust what time 0800 is compared to solar noon rather than have a negotiation between various employers, schools, school busses, school meal subcontractors, etc, to simultaneously replace times people need to be places by +/- 1 hour. Most of the timing isn't formalized to contracts, but is to customary agreements.