Ask HN: Why is there so much focus on American inequality but not on Global?

Average American is still living a life of best standards than a large part of the world.

Why is there so much focus on American equality and none on global inequality?

Is it accepted as a fact that to have a life of higher European/American standard, it's a must to keep half of the world in desperate position? Afterall someone has to stay at the bottom, then only some can be on the top?