It never occurred to me to be puzzled/annoyed by the categories in the US Kindle Deal of the Day (but I will probably find myself so, now!).
What has consistently puzzled/annoyed me is that the description does not by default include the author's name-- and it's frequently not readable to me on the thumbnail of the cover, so I'm forced to click through to find it (and perhaps that's Amazon's clever plan....). Since my book choices are more author-driven than synopsis-driven, it seems a strange choice, and particularly unfair to the author. (The book title is more critical than the author's name? Really??)
I did email Amazon to ask about this a number of months ago, and got polite reply that they understood my comment, & perhaps they would consider a change to list the author: and I have noticed that the author is listed in the description more frequently (but far from always.) At least the Amazon answer I got showed evidence that they'd actually read me query & thought about it, instead of the form-letter response I expected to get.