Why must I sign a credit card receipt for tap and go ?????

They are the only store in the WORLD that when you tap your credit card, they then ask you to sign the slip. Why must I touch a dirty pen that is handed to me and probably never sanitized. Why must I take the extra time out my busy day to do this. With modern technology, signing anything these days is going back to the ark ages. I now refuse to shop at Checkers because of this. I will avoid them at all cost.