One consistent issue we face as hosts are guests who check-out late and claim they didn't know what time check-out was and we have to kindly kick them out. We do manually communicate that info but an automated message sent to the guests the night before check-out reminding them of the check-out time would be immensely helpful.
It would educate the guests and also make the experience neutral so hosts aren't perceived as trying to kick out guests or being eager to see them leave. Perhaps this is already in place which would link back to my request for a preview page where I can see what communication guests receive from AirBnB.