San Francisco resident Randol White says he heard the noises for the first time about two weeks ago -- he was woken up around 4 a.m. to the Waymos honking at each other.
There was a short story by Isaac Asimov that had robotic cars on a farm that some old guy salvaged. At the end, they were all honking at each other to communicate. I won't spoil the story in case anyone wants to read it. It is in The Complete Robot collection. I'll just say it was creepy.