A recent study into kids and video games put forth an observation, these kids who play hour after hour of these killing games have an almost reflexive ability to shoot.
Generally not accurately but they are moving from a hit to the next without the thought process that a normal person would have.
(Just like the kids in the video)

Why? The mental conditioning that they are receiving.
Now give them a jam like the Parkland shooter had and they have no clue,because it doesn’t happen in the game.

There is more here than meets the eye, conspiracy level might be pushing it, when laziness and apathy will suffice.