P2P app could display (orders taken ever), (orders successfully delivered) for every courier. That would be good enough for 90% of costumers, but wouldn't cover the cost of actual fraud for the client.
I disagree with that—I don’t think it would be good enough for 90% of customers. I think it would be about the reverse. Maybe it would be good enough for 10% of customers.
Is there something stopping a malicious peer client from lying about those numbers?
Genuinely curious; I've been wondering about how to make a zero-knowledge P2P protocol for turn-based imperfect knowledge games and this sounds directly applicable to that.