I wonder how much money any retailer is actually saving by not taking Amex. Although the Amex fees are higher than the Visa/MC fees on average, the Visa/MC fees vary greatly depending on the type of card. The high-end cards (such as those used for account types that award miles) have significantly higher discount rates than do standard cards. For the merchants that don't take Amex and force me to use a branded airline MC/Visa, I doubt very much that they're saving much of anything on my transactions.