I once signed STOLEN on a pad at the grocery checkout. They let it ride and ran the charge.

But I was relieved to find my CC provider calling me to verify I was just up to shenanigans.

I was also curious how many thieves they had run across that signed for purchases as stolen in large cap letters.

What do you think the signature is for? If a store can provide a signed receipt, the bank eats a chargeback. If they can't, the business pays. No one verifies that it is your signature. It is just an anachronism of how contracts work.