Actually, Amex was one of the first cards to analyze transaction history and decline out-of-pattern charges. Over the last 20-something years they have developed a pretty solid algorithm. Bank of America, on the other hand, either over-flags (and then keeps you on hold for several hours because they did the same to everyone else) or doesn't flag at all (wow - you travelled from Dillard's in Scottsdale to Dubai in ten minutes! Sure, we'll approve that!)
In regards to the OP's card being declined for fraud, he has said he never goes out of his house and suddenly buys a prepaid card at Target. A fraud filter will flag that. Try seven times before calling the bank? You are lucky your card was not cancelled.