Credit Card Signatures

One of the managers at my place of work had an interesting experience while shopping:

"It happens every day in New Zealand   I was signing the receipt for my credit card purchase when the shop assistant noticed I had not signed my name on the back of the credit card. She informed me that she could not complete the transaction unless the card was signed.   When I asked why, she explained that it was necessary to compare the signature I had just signed on the receipt. So I signed the credit card in front of her.   She carefully compared the signature to the one I had just signed on the receipt.   As luck would have it, they matched."