Humans, as a rule, pretty much stink at risk analysis when the situation is complex. (Some humans, as evidenced by the on-going Darwin Awards competition, stink at it when the situation is simple, but that’s a different post.)
Wired commentator Bruce Schneier notes this and has some interesting insights into how this simple fact of psychological life leads to over-reactions and other irrational acts in the wake of events like the Virginia Tech shootings.
Are you listening, legislators?