[nkrisc]

No, that's not the case. When I'm in New York, most stores open at 9 in the morning. When I'm in London, most stores open at 9 in the morning.

If we all used UTC around the world, I'd have to calculate the difference for all the times that I'm used to. In London the stores open at 9 in the morning, but if I travel East a bit into Europe they open at 12, and dinner is at 11.

It has nothing to do with jet lag. Currently you only have to do any time calculation is you're working across time zones, once you're there and dealing with things in that time zone there's no real difference from what you're used to.