Apparently they are not civilized humans either. It should be instinctive to try to protect someone from attack.
"It should be instinctive to try to protect someone from attack."
No, self preservation is an instinct. Jumping into a melee that one has no knowledge of nor is any of ones business is idiocy.
How about this. The girl being attacked is out on bail for killing the four other girls innocent ten year old brother via a stray bullet in a drive by shooting. The girls notice her in the store and decide to exact a little family revenge.
Still want to jump in?