Nullify the Karen reviews sounds great, but how do we do that? The reviewee can't be trusted to not be 100% unbiased in their review of the reviewer (if that makes sense), obviously. So how exactly do we give her a rating?

The problem with review systems is they are always gamed. Like ebay, where after you buy an item there is pressure both from the system itself and the seller to give the seller a 5 star rating. Some (like me) I'm sure resist the pressure, but I'm guessing most people don't. I don't use uber and the like (the taxi union in Japan has gotten them banned from the country, so I haven't even had the chance), but I've read stories about both sides (drivers and customers) gaming the rating system.

So how do design a system that can't be corrupted...? Now that seems like a challenge.