You are assuming that's the main reason people get the question wrong. IMO your assumption seems very unlikely. Your conjecture that taxation affects interpre

You are assuming that's the main reason people get the question wrong. IMO your assumption seems very unlikely. Your conjecture that taxation affects interpretation can be tested by international comparisons, between the US (where shelf prices do not include tax) and another country where shelf prices include tax. A Google Scholar shows this test has been carried out in many other countries, including those where prices include tax. The few papers I skimmed (like https://link.springer.com/article/10.3758/s13428-018-1029-4 https://link.springer.com/article/10.3758/s13428-018-1029-4 ) make no mention of your conjectured effect, suggesting my opinion is widely held. Yes, it's just about impossible to make a word problem which cannot be over-thought, even one based on a real-world example.