Good point. I agree with the overall thesis; there are a lot of things that get increasingly expensive as you approach perfection. (Perfection is still a useful guidestar, but each step toward it has to be made with costs in mind.)

However, I'm not nearly as breezy about $20 billion annually in fraud. Maybe that's fine from the perspective of the merchants and credit card networks. But from the societal perspective, that's subsidizing bad actors. People and groups who will not stop at one kind of crime as they try to grow. People who will divert other people into being parasitic. That's not healthy for society or for the individuals who end up living lives of crime.

So I think the society-optimal level of fraud is way below the merchant-acceptable amount of fraud.