Earlier quoted context omitted.
Because terrorism is more unpredictable. If you don't want to get struck by lightning, stay inside when it storms, or at least don't stand in the middle of an empty field. If you don't want to be killed by a terrorist, don't go outside at all?
Avoiding terrorism is pretty easy: avoid the busy parts of the largest cities. Nobody is carrying out a terrorist attack in Boise. Which is ironic that the Americans who appear to be the most fearful of terrorism are the ones who live in places where it will most likely never happen.
http://www.idahostatesman.com/news/local/crime/article536103...
Can we agree that the conditions for lightning are fairly predictable, and staying safe is pretty straightforward? Whereas "just don't be where all the people are" is by definition advice that most people can't or won't follow.
Honestly I don't think this point is really debatable. Unpredictability is a core characteristic of terrorism. If tomorrow all Americans decided to spread homogeneously across the country and never congregate in large groups, terrorists would think of something else. If it were predictable and avoidable it wouldn't be as scary, which is the whole point of this conversation.