https://phys.org/news/2018-11-merchants-require-signatures-credit-card.html

The decision was a long time coming. Back in the day, validating a signature was the primary way a merchant could protect against a fraudulent transaction. Today, billions of transactions take place online and the ones that do occur in a store or restaurant use EMV chips and other methods like contact-less devices, biometric readers and PINs that provide a much stronger deterrent against fraud. So much so that, according to Visa, merchants who have been accepting EMV chip-enabled cards have seen a 75 percent drop in counterfeit transactions since they were introduced back in 2015.

"You don't have to sign for your purchases unless the merchant requires it," Linda Kirpatrick, who is the Executive Vice President in charge of Merchants and Acceptance in the U.S. for MasterCard told me. "It doesn't matter to us either way."