I don't know if he really meant that the mob doesn't kill innocents as much as he means that they don't kill randomly. They also don't kill anybody based on what color t-shirt they're wearing.
As far as gangs killing randomly, the headlight flashing story was an urban legend. And your typical civilian in a neighborhood isn't killed every day based on the choice of his shirt color. We must be talking about a period of a gang war and the shirt color or football jersey helps identify rival gang members. There's been plenty of LCN mob wars, also.
As far as drive by shootings, the Al D'Arco biography refers to one. That doesn't prove that it happens all of the time, nor does it prove that it never happens.
