“And yet there was surely a physical meeting where someone handed over a key?”
The past three times I went on vacation and rented a house, the key was “hidden” under a placemat or in one of those fake rock things.
Some people that own houses they rent in tourist areas may never set foot in them. They’ll hire a service to clean the home before/after the visitors arrive/leave and put the key where it needs to be prior to arrival.
I’m sure things are OK 99.9% of the time ... it’s that 0.1% that’ll make you regret employing such a nonchalant attitude with your rental property :-).
Mixed liability.
What a mess.