What you're implicitly arguing is that since we don't prosecute injustice evenly, we shouldn't prosecute injustice at all. There's always going to be something worse happening, it shouldn't distract us from doing what is right. You could easily make the argument that since we allow North Korea to have prison camps, we can't throw murderers into prison because actual justice doesn't exist evenly around the world.

Also finish the food on your plate, there are starving kids in Africa.