It’s hard to answer that without actually seeing a modern gift economy in action. Luckily, modern gift economies actually do exist. On a small scale, they exist among friends, who might lend each other a vacuum or a cup of flour. There’s even an example of a gift economy on a much larger scale, albeit one that’s not always in operation: The Rainbow Gathering, an annual festival in which about 10,000 people gather for a month in the woods (it rotates among various national forests around the country each year) and agree not to bring any money. Groups of attendees set up “kitchens,” in which they prepare and serve food for thousands of people every day, all for free. Classical economists might guess that people would take advantage of such a system, but, sure enough, everyone is fed, and the people who don’t cook play music, set up trails, teach classes, gather firewood, and perform in plays, among other things.
Anthropologists have argued, in contrast, "that when something resembling barter does occur in stateless societies it is almost always between strangers." Barter occurred between strangers, not fellow villagers, and hence cannot be used to naturalistically explain the origin of money without the state. Since most people engaged in trade knew each other, exchange was fostered through the extension of credit. Marcel Mauss, author of 'The Gift', argued that the first economic contracts were to not act in one's economic self-interest, and that before money, exchange was fostered through the processes of reciprocity and redistribution, not barter. Everyday exchange relations in such societies are characterized by generalized reciprocity, or a non-calculative familial "communism" where each takes according to their needs, and gives as they have.
While Swapsity trades are facilitated online, its participants can be seen in real life at themed in-person swap meets as well as the annual Live Green Toronto Festival. Over the past three years, more than 25,000 items—primarily clothes, books, CDs and DVDs—have been swapped at its events, collectively saving people roughly $200,000. About 5,000 items have been donated to charity. On average, each participant saves $80 at every swap (the value of items they go home with and would have otherwise bought). This year’s Live Green event was packed despite the grey July weather: until it started to rain heavily in the late afternoon, lineups to get into the six swapping tents spanned the full length of the waiting area, then folded in on themselves like accordions. Even in the rain, the leaking tents bustled.