As long as the signature is for the cardholder to confirm the consumption. If you swipe your card and say that you didn't swipe it that time, people can produce evidence that you signed for confirmation. If you didn't sign it, you said that you didn't swipe your card that time, so it would be difficult for them to confirm it. But now it needs to be monitored near the pos card. There are actually many ways to prove it. That thing is more direct and uncontroversial.