Honestly I had never heard of the truck crash you cited in your OP until you posted it, and don't know much about it, other than that it's obviously very sad to have so many lives ended at once, particularly because some of them are kids.
As for Aurora, I'd say that event is particularly sad for me because the situation is one I have so often been in, and that makes it easier to identify with the victims and the terror and shock they must have experienced. It's obviously tragic when decent people are mowed down by a psycho this way, but I find it easier to relate to the Aurora victims than, say, people killed by a suicide bomber in Tikrit, so this incident hit home in a way that would not. Also I've always been fascinated by the psychological dynamics that underlie aberrant behavior, and the Aurora case interests me for that reason.
I'm not sure why you keep claiming, when the evidence proves the opposite, that Aurora has some particular political resonance for me. Look at the Aurora threads and see what I have to say about guns. You are just repeating that canard because you assume I am as politically one-dimensional as you - I'm not.