The problem is probably related to the alerting system being automatic. The rate of fraud is likely much higher than we all can imagine, I once read a number ab

The problem is probably related to the alerting system being automatic. The rate of fraud is likely much higher than we all can imagine, I once read a number about credit cards, which was incredible. And if you know the constraints of classifiers where recall and precision are a tradeoff, and consider that basically fraud cannot happen for economic reasons, you can imagine that yanking up the recall (loss avoidance) at the expense of precision (stomping over innocent false positives) is tempting and lucrative, at least on short term.