Yep, I was talking generally, but merchants have numbers to call and if the card is present that's all they have to do and then put the cardholder on the phone to the credit card company and leave it to the card company to decide if it's OK to accept the card having spoken to the cardholder and done security checks. Cards over the phone or online are completely different obviously.
If a shop suggested that my card/transaction might be fraudulent I'd bloody insist they called the card company, if I was there with the card.
Or make the call yourself in front of them?