I’m not sure how these things work to often but have you tried changing your region setting?
Adside from that I 100% agree with you that it does seem a bit unfair to other players who don’t live in the U.S. but I’d like to believe that they have their reasons for this or maybe some circumstances are preventing them from allowing this.
Maybe this case could be similar as it is with other games from different countries, for example: I got into this game from Japan really awesome but when I tried playing the American version nearly half the original content was gone which was really disappointing and frustrating. When I asked the creators why that was they said that their American counterparts hadn’t yet come around to completely adapting the game for American use; meaning that they hadn’t yet fully translated it yet and voiced over the original voices and reviewed over all game content to see if it would be suitable for Americans in terms of content. In such cases where it’d be unsuitable then they would simply remove that content from the game. It especially takes a longer a time to accomplish those tasks if the foreign counterpart team is really small. There’s a lot more then people tend to think that goes into making a game after all.
But this is just 1 of many possibilities. I’m not sure how KI manages or operates their game especially when it comes to availability in other countries so I can’t say for sure nor can I speak on behalf of them.