You may well have simplified/stated things more absolutely for the sake of this point, but... I think in this very post you make the exact mistake you're talki

You may well have simplified/stated things more absolutely for the sake of this point, but... I think in this very post you make the exact mistake you're talking about. You yourself even identify a simple lack of knowledge as a possible cause of these statements. Yet immediately afterwards you jump straight to essentially writing this hypothetical person off, instead of giving them the empathy and understanding that they may be overlooking something, or even entirely unaware of relevant information. It's very easy for people to over-generalize from their own experience. It's all anybody has. Thinking hard is also relatively expensive, so we can need some prompting to actually do it. I think it's worth having some empathy and consideration for people who've stumbled into these unfortunate tendencies of ours.