For as long as credit cards have existed merchants have been conditioned to require cardholders to sign each sales slip. In reality, this process slows down the transaction and adds very little security because most merchants do not take the time to verify the signature on the receipt matches the signature on the back of the card.
Recently MasterCard announced they will remove the requirement to obtain a signature on most transactions beginning in April of 2018. Almost immediately American Express, Discover and Visa followed suit on a similar timeline