And so do individuals. There's plenty of tragic or difficult moments that come unexpected in one's life, and it's easy to make them cover for unrelated issues, because questioning the explanation would be greatly untactful. A somewhat stereotypical example - a student that excuses their lack of homework and unpreparedness by mentioning their aunt died, even though they weren't really close with their aunt and they learned about the death an hour before the class started - it's an easy way out that nobody will dare question.