Re: SD Question - Pizza Parlor Attack
About all the passive bystanders, who are blamed by some for just doing nothing: psychology has shown that this is the most common reaction, expecting that someone else will intervene.
Some numbers: if people thought they were the only witness to an assualt, 85% came to the aid of the victim after on average 52 seconds; if they thought there were 4 other witnesses, 31% did something after 166 secs on average.
And a horrible story to illustrate my point furhter: Kitty Genovese was beaten to death in 30 minutes, there were 38 witnesses living nearby, hearing her scream and seeing what happened from their windows. Not one of them came to her aid.
(Numbers and story come from my psychology class at university.)
So ironically, if there were fewer people in that pizza parlor the victim might have gotten some help.