> I think you missed my point. Weren't timezones created so that the clock could "match" the sun?

Ahh...but what does it mean to match the sun? Imagine a society before we invented accurate clocks and powerful lights. Their point of reference for time would probably be would probably be when it gets light enough in the morning to start work.

Now imagine they discover some kind of material that they can make rope out of, and rope made out of this material if lit on fire on one end slowly burns through the rope at a consistent steady rate.

They invent their first clock using this. In the village some official every morning hangs one of these ropes in the town square a little before sunrise. Each day the rope is the same length. When the official sees sunrise he lights the bottom of the rope.

People then use the rope as a clock, naming times by how much rope is left at that time ("The blacksmith said my sword would be ready by 3 feet today").

It is hard not to say that these people's clock matches the sun, considering that they sync their clock to the sun every day. Sunrise is always the same time for them.

Now imagine a time traveler from our time. He goes back to observe the village. He has a modern clock, set for the modern time zone that the village location is in. The time traveler sees that every day when his clock says it is noon, the sun is in the same place in the sky, close to its culmination point.

So look at what we have. Villagers, with a clock that matches the sun (the sun is on the Eastern horizon at the same time every day on their clock), and a visitor with a clock that matches the sun (the sun is at the same near-culmination point at the same every day on his clock).

So we have two clocks, both clearly matching the sun...yet the villagers will see the time traveler's clock as drifting back and forth relative to the sun, and the time traveler will see villagers' clock as drifting back and forth relative to the sun!

The advantage of the villagers' way of matching the sun is that it lines up our time keeping with our natural activity schedule.

The advantage of the time traveler's way is that it is that the interval from a given clock time on one day to the same clock time on the next day is exactly 86400 seconds.

You can view DST as a way to combine both systems. We run an 86400 second day, but as the amount of daylight increases as summer approaches, the clock gets out of alignment with our natural schedule. So we throw in one day where we do a jump on the clock to align it better with our natural schedule. The as winter approaches, and daylight decreases, we reach a point where we are getting too far away from the natural schedule again, so we jump the clock back the other way.

Seen this way, you can view view the villagers' system as a kind of continuous daylight savings time. Instead of letting the clock get out of sync with our natural schedule and then having a big correction, they make a tiny correction every morning.

> why can't we just change the TIME of a workday, instead of changing our whole TIMEZONE?

Changing the time we do things means that everyplace that we list times for repeating events that could otherwise be static have to be dynamic, or we have to require people to mentally subtract an hour during DST.

Changing the clocks means that all we have to change are things that are already dynamic.