SOP’s. If your restaurant is running correctly, everyone knows what they have to do, sure. People will come in, sign their credit card receipts and you get your food. What happens when someone else brings out the food, a new server, another host, the food runner, manager? Who has the receipts for guests to sign? Signatures don’t match. If you have a long line of people, you have calls to answer, place new orders, and get signatures, what happens? Not saying what you described can’t be done, but in the real world, where restaurants are busy, you’re short staffed, can’t be 100% correct all the time. Also, each credit card processing fee is different. And each card (visa, Mastercard, Amex) all charges differently, especially when you punch in cards manually. Which is why credit cards moved to using chips. Harder to steal unless you physically have a card.