I love the story about unbalanced reciprocity. It reminds me of what goes on in “developed” countries with small-scale neighborhood commerce where there is a high likelihood of repeat interactions.
I’m wondering if one of the distinctions between hunter-gatherer and agricultural here is the frequency of the trade interactions. If a hunter-gatherer were to trade for something like a knife, that knife would last a very long time. It might be a very long time between such trade events. On the other hand, in an agricultural society, the trading of foodstuffs could happen as often as daily, and hence be much easier to observe.