Stop trying to predict categories as the algorithm can't properly do it.
B H commented
Actually, it CAN properly do it if the OP uses relevant keywords in their question. If the algorithm gets it wrong, the OP can move their question (which requires no more clicks than if the OP had to select a category before posting). With the algorithm there's a fair chance the question will land in the right category, saving the OP those clicks. Some users preface their question with one or more keywords from the subcategory heading, to help their question land in the right place such as "Marriage: .... " or "Polls: ...."
Henry Boyter commented
It is probably correct more than 75% of the time. Much more if the poster uses some guiding keywords. And if they took it away, what would happen? The questions would go into a queue until the user picked the category 100% of the time. Wait, you can do that now. The queue is just the algorithm picked category. Then users would complain about having to pick the category 100% of the time. Your best bet is to write questions with more keywords, but not conflicting keywords.