In all the years we have visited Turkey, I can only think of a few occasions we have used a credit card. One was for a couple of sofas and a chair, for which we did get a discount and we did not pay any extra to use the card. One for a piece of jewellery. The last one when we put in a new kitchen. Even when we put in a new shower room and had the bathroom re-fitted, the shop asked use to pay cash and they would give us a discount.
We always use cash in restaurants and for general shopping as I know having had a credit card machine myself, that the charges put a dent in profits. I used to pay a monthly fee to rent the machine and a percentage charge for all sales, which was drawn from my Business Bank Account every month. There was even a charge for debit cards.