Random Acts of Rudeness

How do people reach a point where they truly feel it's ok to violate the rights of another life? I don't mean abortion or death penalty, although very important issues each in their own right. I'm referring to those of us lumped into the human collective. We live, we work, we consume, we..... The most undeniable common denominator is that ultimately, willingly or not - we coexist. One would think then, that perhaps "perfecting" that coexistence dynamic would be a priority for most of us.