Terence Tao would have said this is the difference between a "mathematical problem" and a "real life problem". Kinda like a "treasure hunt" compared to actual archeological activity: you know wits are going to be more important than brute-strength ugly methods... although IRL Brute Strength and ugly approximations are what you end up using the most.
I'm mostly asking this open question to those among us who are well-versed in developmental psychology (I'm mostly thinking of children) . Although, failing the actual scientific research on the topic, I guess some testable hypotheses would be great too.