Comment by tsax

I suffered from Amex's fraud detection algorithm recently when trying to book a discount airfare. There was 1 ticket left, I tried paying for it, and Amex blocked the charge, and by the time I tried it again (90 seconds or so), the ticket was gone. I was on call with many service reps, and no one was able to cover the differential between the cheapest new flight and the discount fare that I missed due to the 'false positive' fraud block. Why should the customer suffer penalties for false positives? Considering that fraudulent charges themselves do not accrue liability for the customer, why should false positives do so?