I used to be a cop. In police training, it is constantly emphasized that you do not shoot at a person driving a car. What could happen if you shoot at a car:

1. You hit the driver, he loses control, and now the car is a weapon, out of control and potentially heading towards innocent people.
2. You miss, but you hit something else (In this case, a child).
3. You miss, nobody gets hit, but the driver gets away.

None of the outcomes are good. Some are worse than others. It's better to just not shoot.

These cops did bad.