Shooting into a moving car is insanely dangerous. The expected outcome is an uncontrolled moving car.
This doesn't mean cops should be making a habit of having high speed shootouts on freeway; nobody wants that. It means the rules need to allow reasonable leeway for people to do what they think is appropriate in the unique situations they encounter. Blanket bans enacted by people reasoning about generalized scenarios are not a good idea. Those sort of absolute rules are too simplistic to be good for anything other than pandering to crowds.
It would be like using a single child’s death caused by a vaccine as the reason to ban all vaccines.
Simply put, such a policy to save far more lives that it would cost, which must count for something. Or perhaps we should also stop using seatbelts and airbags.