Not to deny that this is an example of someone who does not think abstractly -- I agree that it is -- but there's also a Gricean interpretation: From the subject's point of view, if the experimenter already knows that there is literally not even one camel in all of Germany including all of its cities and villages, then the experimenter would not ask whether there are camels in a specific city in Germany, therefore the experimenter must mean, "There are no camels in Germany not counting the cities", or "There are extremely few camels in Germany".