Payment with credit cards that offer cash-back and other percentage-based incentives charge those incentives to the vendors, so it hits their bottom lines. Use of the cards has exploded because of these card features, and those are in addition to typical interchange fees that were about 2%. I have watched my own credit card exchange charges to my business triple over the last five years, to levels I find unreasonable because I cannot just raise prices to compensate. So I charge 4% for credit cards and, not surprisingly, people have returned to writing checks.
The major card companies have over a 50% profit margin (56% recently with Visa or Mastercard). Buyers eventually can expect higher prices or convenience/technology fees.

