I agree with this in principle - but in practice the odds are no one will pick up your order if there is no tip. What I would love to see is a rating system somewhat like eBay where both the delivery driver and person doing the order gets feedback. Drivers that don't maintain a certain level of customer satisfaction aren't allowed to pick up orders. Tips are only given after the fact. But at the same time drivers give feedback on customers. So a customer with a history of not tipping won't get their order picked up.