how so? when a card is fraudulently used to make purchases, AmEx is not refunding you from their own pockets. they take back the money from the merchant it was fraudulently spent with (a chargeback). no loss at all on their side.
not really, prices are based on market demand. the market does not care about fraud issues and such.
whatever the theoretical rise in price would be (due to the fraud), don't you think the merchant would price things at that level in the first place to make extra profit, if they could?