@Irene0: as to why people don't know/realise, it seems that a lot of detail gets lost in plain sight. The more detailed the listing, the less it's read?
Besides everything you're already doing and Andrea's suggestion, you could put in a friendly one-liner house rule stating something like "no. x: All info. on keys and directions provided at booking confirmation."
If you're not using instant book and just prior to accepting their booking request, send a short message letting them know you're happy to have them stay and to make sure everything goes smoothly on arrival, kindly copy-paste rule x in their reply to you so that you can accept their request and have them receive their confirmed booking.
Hoping that doesn't come across as patronising.