Curiosity on my part, regarding your inference that no one had the ...common decency? to follow someone who just caused an accident, retrieved a backpack, and left the scene of the accident that looked like it caused injury (my understanding is that makes him a felon). I heard people yelling (to follow him? identifying him? I'm not a video testimony expert), and saw a few people head in the direction he went. He didn't saunter off, he fuckin ran.
It seems off-putting that you appear to hold society in general in contempt cause no one immediately gave chase/attempted to tackle the guy, but those exact same set of circumstances are grounds for a possible use-of-deadly force by the police if things go awry, with officer safety and split second decisions all that are needed to justify shooting an occasional innocent.
I hope I don't come off as antagonistic, or trolling, or whatever. That is not my intent. Not to make up scenarios to fit my point of view, but it isn't a stretch of the imagination to picture an officer shooting the bad guy just for reaching into the back of his truck, let alone grabbing a backpack and running away.