system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why I have to sign my credit card receipt when I can scribble just anything on there?
gpt
The signature isn't about confirming that you are you. They're never going to check your signature against the one on your card or the one on your credit card contract.

In short? A receipt, in itself, is a contract between you and the person you're buying from. You can make any mark on the line and it legally constitutes a signature. By signing the receipt, you're signing a contract agreeing to the charges listed on the receipt. Two copies exist so that they can make sure you don't underpay them, and so that you can make sure they don't overcharge you.