[gdw2]

I would imagine for many places, a normal 'day' would actually be split across two dates. That would be confusing!

[henrikschroder]

Yes, it would be extremely confusing!

Let's say you have a coffee shop in Hawaii. You are closed Sundays.

You are of course closed in the middle of the "day" on Sunday, because it's nighttime where you are. Which daylight period are you closed? The period that starts on Saturday but continues into Sunday, or the period that starts on Sunday and continues into Monday? What do you write on the door of your coffee shop?

Having a single timezone is such a stupid idea, and yet someone brings it up again and again and again and again.