There are two ways in which that is an over-simplification:

(1) There can be degrees of safety. The fruit might not be either perfectly safe or perfectly unsafe. It might be safe for some people, other people might have allergies to it that could range from mild to deadly.

(2) An observer could be mistaken in their identification of the fruit. It might like one that is safe but night be unsafe. Mushroom are notorious for having dangerous varieties that look like safe ones.