In original timekeeping, sunrise was 6:00 a.m.
In more sophiticated areas, noon was noon.
But noon shifts with longitude. 60 miles is about 1 minute.
The railroads needed standard times to run on schedule, and that is how we got the time zones.
https://www.timeanddate.com/time/time-zones-history.html
Uniform time zones used to be somewhat useful for commerce. But not anymore. In a global economy world most of us are doing business with folks in all manner of times usually not even knowing. Our CEO loves doing townhalls where we all have to conference in. They happen at 9AM where ever he is. And since we’re all the way around the planet that sucks and doesn’t for others.