I did doordash for years, let me explain how it works and what the reddit drivers tell you-
Food Delivery apps isnt a tip though, its a bid.
Tip implies its based on service, where its more accurate to call it a bid for service, against other orders.
Driver is waiting for an order, he gets a 5.00 order(3 from the app, 2 for tip) he declines it cause he has to make atleast 25.00 an hour, and this 5 dollar order could take 20 minutes, not worth it. Then he gets a 15.00 order(5 from the app, 10.00 tip) and he damn near breaks his phones touchscreen trying to confirm the order.
Thats how they work. And the drivers know whether its a tip or not based on distance. A 10.00 order going 10+ miles means its not a tip, whereas a 10.00 order going 1-5 miles is a tip cause of the amount based on the distance.