Some digital music stores restrict their services to certain countries. This may be regulated release-wise (iTunes will not sell certain releases outside of certain countries) or site-wise (Qobuz is only available in certain countries). This has the consequence that although a release is available online, it hasn't been released
[Worldwide]. For this reason, it is easiest to find one country where the release is available and use that as the release country, ignoring all other countries it may be available in.
What digital music stores are worldwide, and which aren't?
I think it would be useful to compile a list of stores that don't restrict their services, and possibly even make a wiki page. If a given release is available on such a store, it means it is available worldwide. I can only think of Bandcamp(?), but there should be more of them.
Restricted stores should also be listed to discourage editors from adding their releases as worldwide. For store with site-wide restrictions only, it would be useful to list the serviced countries so they can be added for every release. These stores may also restrict by release, so beware!
If you know any specifics about the restrictions of iTunes, Amazon, Qobuz, Klicktrack, Beatport or any other store, please post!