Question. And I'm genuinely curious.
How would people feel if someone who was licensed to carry started to open fire on the car and killed the driver? What if they weren't licenced to carry? How do you think people would react to that scenario?
That could just make it worse, he probably drives automatic, if in spasm he'll push the pedal to the medal he could just keep plowing somehow. Besides, you'd be shooting in a mass of humans! All fleeing in panic, and they are everywhere. So not only would you have to make the decision to shoot in under a few seconds, you'd:
1. Have to get your gun from it's holster.
2. Mind your breathing, firing a firearm takes time and breathing, especially a pistol.
3. 2 is important as there are a lot of innocents around, and you will hit them if you don't mind 2.
4. Once you got a clear shot, squeeze the trigger and hope your first shot lands.
All of this has to happen in under 2 seconds as the car passes you, reminder: Humans take a second or two in an emergency to react. Our reaction is not instant, outside of a few instinctive ones. Our brain cheats a lot in reaction time.
And that is all not taking into account that you'd be shooting into a mass of humans! That is a very bad idea, and no self respecting cop (I don't know about USA cops) would do that. You'd run a huge risk of hitting others than the driver, and probably will in the confusion. Those that just spray bullets, are idiots, that never did a marksmanship training in their life.