Amazing, simply amazing ...
... how many holes there turn out to be in every banking system.
And the solution? Use various heuristics to tag transactions as "suspect" and investigate the customer. Each and every time.
My hands are itching to try and improve on this, except then I'd have to conform to all the senseless banking red tape (*cough* PCI *cough*, just for starters) and I'd have to rat more on my customers than on the crooks defrauding them, so I'll end up doing what every bank does, wiggle and argue and in the end, compensate, only knowing that the whole thing should've been done better from the start. It's like, I don't know, they're all running windows or something. We could be doing so much better, only we can't because the mindsets, the best current practices and the rules and laws are in the way.
Yet more reason why my banking account still doesn't have this newfangled internet thing attached and I pay cash wherever I'm still allowed to. Which is diminishing here, even though the banking systems that're supposed to replace cash also regularly just fall over and die. Now where'd I leave my tin-foil hat?