That's exactly the problem: the learned "concept" is not general purpose at all. It's (from what we can tell) a bunch of special cases. While the AI may learn as special cases cavities inside carboard boxes and barrels and foxholes, let's say, it still has no general concept of a cavity, nor does it have a concept of "X is large enough to hide Y". This is what children learn (or maybe innately know), but which AIs apparently do not.