People Killing People

It's interesting to note that googling for "people killing people for a reason" (without the quotes) only gives me hits with a little "no" inserted, as in "people killing people for no reason".
If I search for "people killing people for a reason" (with the quotes), however, the only hits I get are from a song by Infected Mushroom called "change the formality".
I don't know why this is, but I can only assume that it has something to do with the fact that there is no real reason to actually kill someone else...