Well, without knowing the full story, it's difficult to determine the key elements. But perhaps the relationship between Buster and Billie is a key element, whether it's a friendship or something more. Another could be the setting where their story takes place.
The 'buster and billie true story' might be about two individuals named Buster and Billie. However, without more context, it's hard to say specifically what it's about. It could be a story of their friendship, a journey they took together, or perhaps some sort of adventure they had.
We don't really know who Buster is just from this title. He could be an ordinary person whose story has been told to illustrate a particular point about having a'mal heart', whether it's about his character flaws or some sort of misfortune he has faced.
Yes, 'Buster Scruggs' is based on a true story. It draws from the real - life experiences and stories of the Old West, which were then adapted and fictionalized for the screen.