Visa and Mastercard control most of all the credit card transactions in the world and they both charge merchants a percentage (e.g. 1.5%) PLUS a small fixed fee

Visa and Mastercard control most of all the credit card transactions in the world and they both charge merchants a percentage (e.g. 1.5%) PLUS a small fixed fee (e.g. 40c). It's that small fixed fee that makes it pointless for $1 transactions cause you just lose too much.