It doesn't matter whether the savings card is signed or not. The merchant cashier asked for signature mainly for security reasons. The savings card can be confirmed by password, and no one will pay attention to it if you sign it casually.

Credit cards need to be signed, which is related to the way credit cards are used internationally. If you use a credit card abroad, you don't need a password, just sign it, so signing is necessary. At first, China's credit card didn't need a password, but it was a custom in China. Banks set the transaction password function according to the national conditions, which is also aimed at UnionPay lines. Other lines like VISA and MASTER do not need passwords.