Actually, think of it this way--say your bank charges you $1.50 for every time you use another bank's ATM. And say you normally take cash out three times a month, so your bank is losing out on $4.50 a month.

AMEX skims roughly 2-3% off every transaction you make (last that I read). I have no idea how much the issuing bank gets of that, but just for argument's sake, let's just say your bank gets 2.5% of your AMEX charges. At 2.5%, you'd only have to charge $180 worth of goods/services to equal paying $4.50 in ATM fees. Since I charge so much on my CC, my monthly CC bill is far, far larger than $180 every month and I suspect that yours is, too.

OK, so maybe your bank isn't get all of that merchant fee, but some combination of companies other than the merchant is getting that money.