According to the Measures for the Supervision and Administration of Credit Card Business of Commercial Banks

Article 38 The issuing bank shall publicly and clearly inform the applicant of the application materials and basic requirements, and the application materials must be signed by the applicant himself, and the card shall not be issued without the knowledge of the customer or against the wishes of the customer.

The application materials for the supplementary card of the credit card accepted by the issuing bank must be confirmed by the main cardholder through personal signature, customer service telephone recording, electronic signature or a way recognized by both the cardholder and the issuing bank.

So banks must personally sign credit cards for customers!