If you're running a conference and ask them to get some coke from the bar, they usually have been able to get it (it's also possible they have a secret "guest happiness" stash) - and I've seen them pour it at the bar - Pepsi is from the spigot machine, Coke from a can.
Is that an actual preference or just spite-driven? Nope, sprite is a Coke product, we don't serve that here! But seriously, it's a real preference, it holds for the generics too. Most generic colas seem to be based on the Pepsi taste. Ugh. RC isn't, so RC Cola is fine, but too rare to ever be helpful. Caring about this is a curse!
I don't think this is even true for most of the USA, much less the world. I've never heard anyone refer to anything except a cola as "coke" although I heard that was the vernacular in some subset of the US... some southern US states?
Edit: forgot map
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