Regarding JSON vs XML, I just pointed out that this is an interview question about discussing engineering trade-offs. The purpose of the question was to ensure

Regarding JSON vs XML, I just pointed out that this is an interview question about discussing engineering trade-offs. The purpose of the question was to ensure that the candidate could understanding and evaluate trade-offs without making snap judgements. The candidate was incapable of doing so. For the threading question, the reason why I chose an unusual API was for your exact reason: You'll never see it on a list of interview study questions.