That is not true. Cops are permitted to use deadly force in certain situations to prevent escape. In this case, if an officer was hit, or officers reasonably thought an officer was hit by the car, they would likely be justified in shooting the driver as he drove away. But your statement is emblematic of the real problem here. People that don't know what they are talking about, post things like this and other people read it and believe it resulting in anger based on misinformation.
He supposedly did not drive away. If he did drive away, he would still be in possession of a deadly weapon - the car. In this example he used the car as a deadly weapon so his continued use of the vehicle would suggest he is still a lethal danger. But the article says he fled on foot. In that example, he discarded the weapon. In either case I hardly believe that a reply comment on a website is symptomatic of “the problem”.