Because this world doesn't exist.
But to answer more accurately, this is precisely the difference of culture that makes a travel interesting, at least for tourism. Automatically with the difference of culture comes the difference of language.
There is a lot of theories we can agree with to make the world better, or more simply to improve air safety travel. But we will always have to face reality. And the world is always in move, even shifting sometimes.
My point: a pilot is not here to make theories, he is here to improve safety at his own level. He flies everyday to Russia? So he has to learn russian (at least russian radiocom) if he thinks his situationnal awarness could improve. A pilot cannot change the world, but he defenitely can change himself, or at least adapt, get some language skills, this is the least we can do as we pretend to deserve above average salaries.
But honnestly, I would like to see the numbers/statistics for last year concerning crash involving language as a cause versus all the others.