Do you enjoy taking things out of context? The police knew that they were pursuing a suspect who had a weapon and who had just committed an armed robbery, and who would probably do just about anything to try to avoid being arrested and eventually end up in prison. That is a bit of a different situation than if a person on the street saw a car slowly back up toward them without any information in regard to the driver of the car or the driver's motive at that particular moment.
You're right, it is a different situation. But then again, many people on this thread have told me that it takes but a split second to depress the gas pedal. I have bumped them.