As much as I love a cowboy ghost story, none of the stories featured any explicitly supernatural elements (Buster’s angel aside, we only see that because the story is from Buster’s POV, and the angel doesn’t interact with any of the living characters in the story - harmonizing doesn’t count.)
The bank in Near Algodones was absurdist, but not supernatural (as were Buster’s antics). The wildlife in the All Gold Canyon, similarly were close enough to feel out of place, but still not explicitly supernatural. So, based on the milieu of the other stories in the collection, it seems unlikely that the bounty hunters were literal reapers, or that the passengers were actually dead and therefore spirits.
But, That doesn’t mean that it wasn’t a metaphorical coach ride to the afterlife. The whole story could have played out in exactly that way had they been dead, which is kind of the point. That’s a deliberate construction of the story. It’s illustrative and evocative and metaphorical, but nobody was actually a ghost. I think their reactions at the end work in that regard even without a direct appeal to the supernatural. Nobody wants to acknowledge that they will die one day.
I did get a bit of an “Appointment in Samarra” vibe from it. Like, the Bounty Hunter is Death, but Death is also just a person at the market, and he hasn’t come for you, but for somebody else. But even so, he’s still not a person you want to spend any time with.
I liked Meal Ticket the least, of them all. It was the bleakest, of course, and so generally hard to watch, but I also didn’t care for the storytelling through oration. But then, I very rarely read italic blocks of poems or songs when embedded in novels, because I don’t really care for them. The snippets of the Orator’s speeches that we heard were obviously extremely significant, especially in the later montage section, but I just dislike that mode of communication, so I didn’t really pain close attention to it.