My mom used to tell me to write CHECK ID in the signature block. Someone only ever asked me once. It's probably been like 10 years since I've signed the back of a new card. An older woman at an antique shop actually checked for a signature and made me sign it in front of her.

The fact that a signature is, to date, a legally binding form of identification is baffling to me to be honest. More and more is digital these days, but still.

(my "signature" is just a squiggle based on my initials and I can't reproduce it consistently)