There are probably 25,000 arguments and disputes per day between strangers in public, people flipping others off etc....Most end it by walking away, some even get physical to some extent.
Very few end with one party opening up and shooting to death an unarmed person in public. And the perpetrator usually has a violent history, who's been in the system, in the joint, on parole etc...
This was not an armed robbery or armed assault by any stretch of the imagination.
Yes if I shot everyone who ticked me off in a public place I would have to reload every few minutes. :-)