It's about risk. Visa/MC/AMEX deals with people worldwide, which includes some crooks and thieves that are trying to scam them (and will continue to do so, und

It's about risk. Visa/MC/AMEX deals with people worldwide, which includes some crooks and thieves that are trying to scam them (and will continue to do so, under multiple identities). The coffee shop only deals with customers it sees personally, so it can keep people from scamming them multiple times, or for large amounts. Any business that tries to disrupt Visa/MC/AMEX is going to have to be able to handle and reject large-scale fraud.