The difference between things that can happen through inattention vs a drunk person might do while really pissed vs things that require significant preparation has major implications for how often they occur.

Vehicles are used to kill a great number of people per year, but it’s really unusual to find someone who actually killed 50+ people through a vehicle alone. Meanwhile there’s significantly more people who used bombs to reach those numbers, despite how much more difficult it is to access significant quantities of explosives.