The point is “people can be fooled into making this specific mistake”, which is an indication that that specific mistake is one that people do make in some circumstances, rather than that specific mistake not being made at all. (As a counterexample, I imagine that it would be rather hard to trick someone into claiming that if you put two paperclips in a bowl, and then added two more paperclips to that bowl, and then counted the paperclips, you’d find three—that’s a mistake that people don’t make, even if someone tries to trick them.)
“Some circumstances” might only be “when someone is trying to trick them”, but even if that’s true (which the experiment with the dice suggests it’s not) that’s not as far removed from “living life” as you’re trying to claim—people do try to trick each other in real life, and it’s not too unusual to encounter other situations that are just as tricky as dealing with a malicious human.
The point is “people can be fooled into making this specific mistake”, which is an indication that that specific mistake is one that people do make in some circumstances, rather than that specific mistake not being made at all. (As a counterexample, I imagine that it would be rather hard to trick someone into claiming that if you put two paperclips in a bowl, and then added two more paperclips to that bowl, and then counted the paperclips, you’d find three—that’s a mistake that people don’t make, even if someone tries to trick them.)
“Some circumstances” might only be “when someone is trying to trick them”, but even if that’s true (which the experiment with the dice suggests it’s not) that’s not as far removed from “living life” as you’re trying to claim—people do try to trick each other in real life, and it’s not too unusual to encounter other situations that are just as tricky as dealing with a malicious human.