People can identify things hurting them, but not always correctly. But people also can blame personal failings on external sources easily as well. It’s like as

People can identify things hurting them, but not always correctly. But people also can blame personal failings on external sources easily as well. It’s like asking why studies using self-reported survey numbers on penis sizes cannot be treated as the ultimate truth, despite adults surely being able to use a measurement tape or a ruler. There is a reason for why the average numbers on all those studies using self-reported numbers are always at least one standard deviation larger than the average numbers obtained from a study that wasn’t just a self-reported survey.