Heck, gift economies persist in the modern day. Folks at my work buy each other coffee, spot each other for lunch, etc. all the time, on the understanding that they’ll get you back at some point. Or pay it forward to someone else in the department who will pass it on and it’ll get back to you eventually. When I used to smoke, there was a sort of unwritten code governing the bumming of cigarettes; charging a quarter for a cigarette or whatever was frowned upon, but so was only ever bumming smokes and never having one to spare for someone else. Artists I know do art trades all the time rather than each commissioning the other. I’m sure most handy folks would rather help a friend or neighbor out in exchange for a future favor than charge them. Currency tends to start getting involved when the interactions start getting too complex to easily track, and/or when you don’t know the person you’re trading with well enough to trust they’re good for the debt.