Card-not-present (CNP) interchange is meaningfully higher than card-present interchange because the issuing bank takes more fraud risk. Mail-order and telephone-order (MOTO) transactions, typed into a virtual terminal or invoicing tool, qualify at the highest CNP interchange tier. The result is a 30–80 basis point premium over the same card swiped in person. On flat-rate processors this is invisible (you pay the same flat rate either way and the processor absorbs the loss). On interchange-plus, the higher interchange is itemized line by line.
Not to be confused with surcharging — this is the network-set interchange premium, not a fee passed to the customer. Phone-order businesses can mitigate by capturing AVS and CVV (lowers interchange tier), or by sending text-to-pay links so the customer enters the card themselves on a hosted page (qualifies as e-commerce, slightly cheaper).