A worldbuilding thing people often overlook is the way that cultures are contradictory without anyone really noticing or acknowledging it. Like “in Xland funerals involve covering the corpse with gold leaf and then making a dozen marble statues of the deceased” except, you know, those are only some funerals. Or “In the US in the fifties married women didn’t work outside the home” except that didn’t apply to poor women and plus actually quite a few middle class married women–with kids even–had full time jobs (like my grandmother, who was a social worker in the 50s and actually all the way up to her retirement).
The Sherlock Holmes style of deduction–no native speaker of English would make this particular mispelling! No member of this one religion would ever have/say/do this forbidden thing, therefore Person B must not have done it! Everyone in Society Z was married, so stories about an unmarried adult must be entirely fiction, or they must just not have mentioned a spouse for some reason” all these things assume that cultures are logically consistent in a particular, straightforward way that, frankly, they pretty much never are. Note, I’m not saying you can’t draw any conclusions at all from data about cultures, just, things aren’t hard and fast, certainly not simple, and people generally just don’t see the contradictions or put them in a special “but that’s different” category.