In the end, wouldn't it result in much the same thing? Assuming that we want everyone to know that we're waking up earlier in the summertime and closing up sho

In the end, wouldn't it result in much the same thing? Assuming that we want everyone to know that we're waking up earlier in the summertime and closing up shop later, it would be preferable to coordinate this, right? We couldn't want all banks and shops and things closing at their own time. Or schools starting two minutes earlier every single day as we approach summer, to match up exactly with the sun, right? So we could coordinate it all to happen in one big step. We'd say "Hey, from March 14th onward, all public schools are now going to be starting at 7:30 AM instead of 8:30 AM, and banks will open at 8:00 AM, and post offices will close at 4:00 PM. And then we could so the same thing in the Fall, backwards. But then, with nothing forcing private businesses and private schools from following this, wouldn't we get some horrible mismash? We'd have to call up every restaurant before making a reservation: hey, do you follow personal summertime hours? Banks would have their own closing hours, your older kid's public high school starts 1.5 hours before the private elementary school instead of a half hour, etc etc..