anthropologists have long pointed out that exchange does not always need money.
one famous example is the kula ring in the trobriand islands, where valuable shell necklaces and armbands circulate between communities as gifts. the objects are not simply bought and sold. giving, receiving, and eventually passing them on creates status, trust, obligation, and long term social ties.
that is the interesting part of a gift economy.
the gift may look free, but socially it is rarely empty.