"Western" or "Western World" doesn't just mean geography, but can instead be a code-word for countries with very similar political/economic stances that share a bond with eachother. It all depends on the context. During the cold war, west just meant any US ally.
You mean First (Capitalist) World. But west is strictly geographic.
Everyone follows the greenwitch time because of the simplicity of it... Sure, Russia could say tomorrow that the moscou time zone is GMT 0, but it's just gonna make it a whole mess to comunicate with other countries.
So it is universally recognised. And there are strict longitude lines (I think it's every 15*) that say where each time zone begins and ends - at any rate, Russia's not getting to the middle. Frankly, I think differing timezones in general are just messy, that we should just all go with one timezone, like China has one national timezone, but that's another tale.