It is all a question of scale and accountability.

The problem of terror is that it is costly to track and to deal with. From the viewpoint of the terrorist this is the entire point.

The problem of food is that once a problem is found and pinpointed the producer has a great deal to lose, so there is every effort (or at least there should be) for a producer to produce a safe product.

Food inspectors work on a 'trust but verify' principal, and terrorist work on a 'you never know where I will strike next' principal.

The goals of each group are also so different it is hard to stack one problem up against the other.