Another failure mode can be testing the wrong things. Companies will make products to do well in tests or otherwise appeal to consumers even if that makes their product actually worse. For example maybe tyres would only be tested in a straight line (rather than when cornering) or when unworn (so allowing shallow grooves to allow for a thinner wall and shorter life).
I recently came across a YouTube channel where a guy does various thorough-seeming tests of a medium range of brands for a bunch of product categories (think spanners and scissors and suchlike) and he’ll talk quickly and provide lots of numbers but when you think a little more, it seems that there isn’t much reason for the test results to correlate with a good product (eg maybe if your Phillips head cams out it is because that is what it’s meant to do and not because it’s bad)
I recently came across a YouTube channel where a guy does various thorough-seeming tests of a medium range of brands for a bunch of product categories (think spanners and scissors and suchlike) and he’ll talk quickly and provide lots of numbers but when you think a little more, it seems that there isn’t much reason for the test results to correlate with a good product (eg maybe if your Phillips head cams out it is because that is what it’s meant to do and not because it’s bad)