For regular businesses, the transaction fees (both % and per transaction) are higher for AMEX than VISA or Mastercard. So a lot of small businesses don't take

For regular businesses, the transaction fees (both % and per transaction) are higher for AMEX than VISA or Mastercard. So a lot of small businesses don't take them. With some processors, there's also a monthly fee if you take any AMEX, so it's better to not take it all.