China uses a single timezone where similar width countries use three or more. So some parts start the day at 8am, others start at 10am

If we used a single timezone in the west it would be UTC which is practically on the other side of the world to me - I’m in +11 now, +10 when we go back to standard time in a week. That would make it reasonably easy here, the clock would be out by near enough to 12 hours (if you prefer light in the evening) that you’d be fine on a 12 hour clock just inverting am and pm