I didn't intend it as a general-purpose tool for understanding AI, but as an intuition pump for why this problem is hard for LLMs specifically.

In this case it is actually relevant. The ability to draw a pelican on a bicycle correctly depends a great deal on understanding not only what both look like in general, but on the spatial relationships between the various objects and their parts. Models that can draw this kind of thing better also tend to be better at tasks that require understanding of how things go together and interact in 3D space.