They are just going to be creating more work for themselves.
If I do not want to pay the cash fee then I just buy something and take it to the customer service desk and ask for a cash refund.
They could, of course, do what the gas stations do and have one price for cash and a higher one for charge.
But all of this is straining at gnats.
They are doing something that will send people to other stores if available and will result in unhappy customers where there is not another option. And then soon there will be another option.
None of the stores near me will give you cash refunds on something if you used a debit/credit card to purchase. They'll put it back in the card you used or give you store credit on a gift card.