It's not obvious to me that the example you give is "downright easy, provided you understand the material". Now, I understand the material, and I find the example easy. But I can see that it involves a few little cognitive leaps which it may not be reasonable to expect a student to make. The straightforward solution, I think, involves considering x < 0 and x > 0 separately. How is a student supposed to know that that's a reasonable option? Is "when a question uses the phrase 'the same sign as x', try considering each sign separately" in the textbook? Are students supposed to figure that out somehow?