Seeking a correct answer is trivially easy, though; you can always find the rule "any of the six shapes on the left", just as you can always fit a function to any arbitrary sequence.

Right, but the context is that these problems comprise an evaluation suite for artificial intelligences. Even simply textually describing the shapes on the left and the right, is an accomplishment.

A better test suite would likely provide an oracle capable of generating new images belonging to the left or right and asking the program to judge which side it belongs to.