It's definitely easier trading in caps than trying to trade in, like, brahmin cows. Can you imagine trying to keep brahmin in your pocket? You wouldn't be able to fit very fucking many in there, that's for sure.

A lot of times people skip the currency altogether and just trade goods directly. I'm guessing that that's what you get a lot of around here, too, us all travelling around all the time and everyone from different universes. It's a pain in the ass sometimes, haggling over how many cans of beans a pack of ammo is worth, but hey, commerce. Nothing keeps it down.