Maybe my memory is faulty, but I never remembered having to pay a surcharge to use a credit card. Now everywhere I go there are signs saying that there is a 2.5-3.5% surcharge to use a car (and others that say that there’s a 2.5-3.5% discount for using cash, I assume to get around wording)
More likely, it’s to fudge the numbers and pay less tax. Credit cards leave a record of income. Cash doesn’t.