.eu is not a ccTLD, because the European Union is not a country.

Yes, .eu is a ccTLD. "EU" appears in ISO 3166-1, a list of codes for countries and other geographical purposes, under the Exceptional Reservations category. TLDs in use on the basis of an entry on ISO 3166-1 are known as "country code top-level domains," even if the use of the word country is ambiguous or administratively incorrect.

For example, no one (well, perhaps we should say few) would argue that the United Kingdom of Great Britain and Northern Ireland is not a country, yet it operates ccTLD .uk which is not a country code assigned to a sovereign entity. GB is the country code for that country; UK is an exceptional reservation.

> For example when UK left the EU then all UK registrants of .eu domains were made to relinquish them. No grandfathering. This kind of nonsense doesn't occur on .com

Do you happen to have a source that supports that claim? I've registered .eu domains in the past and I never had to even offer any proof of citizenship or residency or anything of the sort. I searched for the domains, clicked on "buy", and that was that.

The parent is correct, in theory .eu requires residency or citizenship in order to register a domain[1]. After Brexit holders of .eu domains that did not meet the criteria lost their domains[2].

And the .eu is not the most restrictive ! I am a French citizen but live outside the EU, so I can't get a .fr domain (at least, again, in theory - haven't tried in practice) but I could get a .eu one.

[1]: https://eurid.eu/en/register-a-eu-domain/rules-for-eu-domain...

[2]: https://eurid.eu/en/register-a-eu-domain/brexit-notice/

Your registrar isn't doing the necessary due diligence then - mine made me send them a scan of either passport/ID or residency permit.

https://eurid.eu/en/register-a-eu-domain/brexit-notice/