I've said before, if this was a reflex action, it is still a crime, but at least somewhat understandable. A conscious decision to drive into a crowd of pedestrians is pretty much inexcusable IMO.
And as I said before, the two (driver's actions and crowd's actions) are not comparable.
was trying to kill them.
That's debatable. For all the crowd knew, his brakes failed. Hence no "attempt to stop."
I can't say for sure why some members of the crowd immediately attacked the car. Did they have some indication before the crash that it was intentional? Perhaps. The speed the car traveled at, the lack of brake lights, people being forced to jump out of the way as the car made its way down the road, any or all of these might have given the members of the crowd the idea it was intentional.
Perhaps those members of the crowd that attacked the car were simply prone to violence. I won't deny that possibility. Maybe their first reaction to seeing friends or family injured like that is to seek retribution, without worrying about whether it was accidental or intentional. Or it may have been less considered than retribution; more of a lashing out at the thing which just caused such violence, without any clear goal or rationale.
I wasn't so much comparing the two actions, driving into the crowd and the crowd attacking the car, as comparing your reactions to them. You quite easily come up with reasons you think that driving into a crowd of people is a reasonable action, whereas you seem to find the idea of people attacking a vehicle which had just driven into their fellows something for which there cannot be a rational reason. While I believe the driver intentionally hit the crowd, and I disagree that driving into the crowd would be a rational way to try to escape, I certainly can see how a panic reaction could lead to such an accident. I also can see how members of the crowd might feel attacking the car to be appropriate, if they believed it had run into their fellows on purpose.
You have made comments about how the driver did not have time to make a fully thought out, rational decision. That makes sense, at least in the context of the amount of time between the car being hit by the flagpole and the car striking the crowd. How much time did the crowd have to make a rational decision after the crash? Is the lack of time to think the situation through and reach a rational conclusion not applicable to them for some reason?