I'm referring to the fact that it didn't take much psychological difficulties in offing a man's life - irregardless if he was going to live or not.
This is usually the highlight of any zombie flick - because it actually takes a mental strain to those that are accustomed to the modern society when taking the life of a random person. That's pretty psychotic if you think about it (the lack of empathy and excessive self-preservation when said person committing the deed is not in the verge of death), unless they have been doing it for a very long while, considerably desensitized.
Gosh, I hope you get what I'm trying to say XD Words all jumbled up in the morning...
Personally, I think I get what you're saying.
Basically, folks don't simply go around and kill other people... it takes either someone "disturbed" or in forced circumstances to do so...