Interchange qualification and fee calculation is one of my specialties. The article and the graphic are very high level but are generally correct. I would add geographic relationship of the issuer and acquirer as an important part of fee determination that is missing from the graphic. Domestic is generally cheaper than intraregional is generally cheaper than interregional. Lots of banks tried acquiring but found it difficult to pay the interchange fees and still eke out a profit from the merchant business. That difficulty is the reason fewer banks/processors do their own acquiring, preferring to invest in the card issuing and portfolio management side of the business and leave the merchant business to big banks/processors or specialty shops. If your merchant/acquiring software can successfully classify each transaction and set the correct fee level, you have a very good advantage when pricing your merchant services. It's not really all that difficult, but the number of fee programs has grown from 2 (paper vs. electronic) in the mid-1980's to dozens for each card scheme, with new ones every year. Inflexible systems have a problem with this.
