I'm not gonna say that that doesn't happen, but it's surely not the only thing that happens in places without an authority. People want to exchange goods, and they're typically willing to be clever in order to make that happen.

Already cryptocurrencies are implementing webs of trust to guard against this kind of thing (CirclesUBI). There are also things like MAD escrow (particl). And there's the old fashioned way, which is to get the community together and set up your own impromptu government.

I'm not saying that markets function well without readily available trust. But to say that they cease to exist in those contexts is surely taking it too far.