Yep this does not surprise me. Reading the guide it's clear to me that when you say:

> Our goal is not to simulate day-to-day software development

You don't mean at all, you mean in its entirety (so you are leaving out the aspects you are less interested in, like reading stack overflow, and emphasizing the aspects you are more interested in, like reasoning about data structures). I think a lot of people on HN are getting hung up on that sentence, honestly. Thanks for the guide, though, considering something similar for Justworks.

This generally means asking an obscure edge case which was only challenging because you can't Google it and so is a wildly inappropriate question for an interview.