[kelnos]

If the customer had set up the overdraft "loan" feature, then sure, I'd agree with you. But they didn't. How is it sane (and legal) to automatically loan someone money to pay something, without their permission, when you can set whatever repayment terms you want? Declining for insufficient funds is the only correct thing to do in that case. And yes, banks will usually charge a fee for that, too, but at least it'll only be a one-time fee.