The problem with this is that many delivery drivers use the tip to determine if the delivery is worth their time to accept. If you put in $0 (assuming a cash tip at delivery) nobody will want to pick up your order. On average it will arrive later and in worse condition than if you had entered a higher tip into the app. The tipping incentives for online ordering are all backwards.

It would be nice if they just turned it into a "bounty" system. Delivery is "free" to start. You (and the restaurant since they want to make a sale too) can put up whatever number you want to attract a delivery driver to take the job. Like it's super weird but at least it's honest about how these systems work.