bottle caps are the currency of the wasteland in the games, yes. So he's basically making money by removing the caps.So they're collecting bottle caps?
The NCR and legion did mint their own currency, but outside of the those areas, most people deal with Caps because of how prolific and durable they were.
Bottle cap
Bottle caps, also referred to as caps for short, are the standard currency in Fallout, Fallout 3, Fallout: New Vegas, Fallout 4, Fallout 76, Fallout: Brotherhood of Steel and Fallout Shelter. Fallout 2 is an exception, with bottle caps being an archaic currency supplanted by the NCR minted...