Time zone mystery

There are many oddities in time zones.

e.g. China spans the similar width and size as the USA. China chose to have one single time zone for convenience, and leave its people decide when to go to work. As a result, people in NE China go to work at 6am, while those in Xinjiang and Tibet do it at 10am. The upside is that one does not have to adjust the clock and there is no risk of missing train or plane while travelling. There is also little risk of missing phone conference.

But there are more. See this map. The bottom color denotes what the time zone that vertical strip really belongs to. e.g. Malaysia and Singapore belong to Zone 7 (dark blue/purple -- that of Indoneisa and Indo-China), but they chose to be in the same zone as China, perhaps for good practical reason today. (or back in the British colonial era?)

Othe oddity

• Whole of Alaska is shift 1 time zone to that of the SE strip of the capital Juneau (it is doing what China does). Perhaps also such that it is only 1 hr behind PST.
• Argentina chose to align with Brazil by stepping out of the zone it belongs to
• France, Spain, Portugal, Algeria and Morocco went with the EU and left the UK zone.
• The whole ex-USSR seems to be always on summer time