Well, in Germany there is no such law. But a lot of businesses don't charge extra, since its a positive factor for the sales. People tend to spend easier more than they intend - which is hard to do with cash. Also, with the right card you get discount on your purchases. I have a Amazon VISA card, which is free, plus it gives 0.5% discount on all payments outside, and 3% inside Amazon.
But I have seen places, like some restaurants, who charge extra for using a credit card because they get charged a fee by the card company as well. Some even refuse credit cards. Overall, people use mainly direct debit bank cards for shopping here, not the real credit cards. But also for using debit cards the bank charges 10 cent for each payment.