This appears to be a case of overactive adrenalin coupled with old-fashioned panic. Same thing where local Police have emptied their clips into a nutty woman holding a cap pistol to HER OWN head, or rushing into a hostage situation and pumping several shots into the hostage. People get excited and make stupid mistakes. Tragic part is, the publicity makes the dept look bad, and something has to be done.
On the surface, this incident appears to be one of haste and adrenalin, if not a deliberate shooting. If that is the case, the officer should face the same justice as any other person who pulls the trigger in error or anger. Of course, this entire incident, and many others like it, might have been avoided had the driver simply stopped his car when ordered.
In all my years in the hospitality industry, I've had many occasions to interact with law enforcement personnel. The vast majority of those interactions have been with seemingly honest, polite, professional men and women who take their responsibility to the community very seriously. There have been the one or two who should have been stacking boxes in a warehouse. No empathy, LOTS of ego, arrogance and a willingness to intimidate or maybe worse. By far and away my perception of the law enforcement community is positive and I believe they try to discharge their duties to the best of their ability in job that it extremely difficult. I am amazed that in a job so very stressful, there aren't even more shootings, accidental and otherwise.