Some drivers just take your tip and don't bother to even try to get your order right and if they bring you one item of your list and nothing else your tip on the whole order is still theirs you could end up spending more on the tip than they even spent for the couple items you actually get i think you should be able to change your tip if your order is incorrect especially if items are checked off your list and not correct rethink your policy to not just benefit your employees but your customers2