Importantly, it is utterly futile to expect a shop assistant (let's say a waifish 17-year-old girl) to tell a customer (for our purposes today, a 30-year old champion cage fighter still bruised from his last bout) that their signature doesn't look right and they can't complete the transaction. Chip and PIN means any blame and bad feeling is shifted to the terminal -- for better or for worse, "computer says no".