I think it's the other way around. Without the cultural norms around impersonal markets, you have to rely on your extended family network or clan for everything

I think it's the other way around. Without the cultural norms around impersonal markets, you have to rely on your extended family network or clan for everything, because there is no trust otherwise. This is what keeps you from traveling. If you were trying to trade with a far-away stranger, why should they not just rob you instead? Nobody is around to punish. And for all they know, you were just as likely trying to poison them rather than make a fair trade.