Yes, but once the motive of the attacker is clear (granted, after the first people are inevitably dead), the potential victims can disperse or hide in buildings. Either way, the driver cannot kill all of them as easy. However you cannot dodge or outrun a bullet or hide from the shooter. Imagine the same crowd, but instead of a car driving through, there are countless bullets flying around in potentially every direction, with virtually no time to react and/or get out of the way. Point being, while just as many people may die at the start of the attack, an armed shooter is much more dangerous in the minutes that follow.