I dunno, I've picked up my share of hitchhikers and to me it wasn't about being a trade, it's about sharing presence and our stories. Not a transaction, but just sharing.

One time I was stopped on a single lane highway in the mountains, in driving rain, as a power pole was blocking the road. A fellow commuter was in the same boat, but he was on a motorcycle. I invited him in my car and we just chilled and shared some light conversation. No trade, nothing gained besides someone offering a little shelter to another.