None of those are the same country. They are distinct countries.
And the gb / uk thing exists because of the northern ireland situation. Its an exception and a very old one and gb does not refer to uk, but uk does include gb.
Each distinct political area has one tld.
While .io might not have been registered by an inhabitant, the country code it is sourced from WAS used by people living there and continues to be used officially today.
My point is, they should not try to enforce rules they did not enforce in spirit previously. That they even allowed the .io tld to be used at all speaks volumes. It was never used as a country tld. It was always used for people and companies not living there.
Iso country codes are one thing, but top level domains are an internet thing. They could just as well have designed it with the 3 letter iso country codes. That is even more techy. Internet of Things. .iot And Ireland would have .irl which would be very popular I guess, as it also means in real life. Or they could have used any other design for dns and country specific name resolving.
What they did use is the 2 letter iso codes wherever possible and refused to allow 2 letter tld to reserve for new iso codes. But that code is burned in iso. They will not re-use it for another country. So it is free for usage as a general tld. We shall see how sensible they will handle it. Could turn out either way.
