Distance based empathy as mechanism enabling pluralism.

Human empathy drops off over space.

Singer and many people think this is bad. If we cared about injustices which happen rather than letting out of sight be out of mind, the world would be a far less bleak place.

I disagree.

Morality clashes. First in the big things then, once the big things are to your liking, in the little things. (Not seeking to imply process is without limit). Without morality inversely proportional to distance, we would seem to impose our ethics everywhere. War would be constant. Plurality would be impossible.  We struggle to tolerate small differences which are closer to us, pro life vs pro choice. I doubt we would tolerate far larger differences in value, especially if we had the strength to crush those who disagreed.