Headscratchers / Black Mirror: Metalhead

• Why is there a Dog guarding an abandoned warehouse? In a post-apocalyptic future where humans are nearly extinct, what is there that's valuable enough for a non-human to protect?
  • The fact that the Dog is lurking behind the box (instead of wandering around on patrol) suggests that it is preventing people from taking that specific box. Why would a Killer Robot need to watch over a box of teddy bears?