The idea that these word problems (and other LLM stumpers) are "easily solvable by humans" needs some empirical data behind it. Computer people like puzzles, and this kind of thing seems straightforward to them. I think the percentage of the general population who would get these puzzles right with the same time constraints LLMs are subjected to is much lower than the authors would expect, and that the LLMs are right…
I wonder if these models, trained on data from across the internet, are in some ethereal way capturing the cognitive approaches of the average person (and not picking the best approaches). If the average person does not think in these sorts of symbolic-manipulative terms, and therefore does not write in those terms, and you train a model on that writing...?