Could be a lot of reasons, but probably the fact that the movies are so talky doesn't help. American films with lots of action that are less dialogue-reliant do better outside the English-speaking markets.
Somehow, I hope you're being sarcastic here...
I've noticed that superhero films almost always make more money within the US alone than internationally. Maybe this film is somehow regarded as being in line with 'Batman', 'Iron Man', 'X Men', etc.
But to state that people outside the US prefer 'big dumb action films' over films that are more dialogue driven is a pretty bold statement. Films like 'Troy', 'Kingdom Of Heaven', etc., have performed badly in the US, but did very well internationally..!
I do think Trek is very, very popular outside the US, and it showes when it comes to DVD sales. I'm not sure why not more people outside the US go see a Star Trek film in the cinema.