1) Drivers have no control over how long it takes for the restaurants to make the food.
2) Drivers can see whether or not you tipped before they accept the offer. No tip offers are more often than not rejected by the drivers.
OR if the tip is low like $1-$2 they make you come outside to get your food.
Drivers are independent contractors.
They have to use their gas and their car to pick up your order. If you cannot afford to tip, then go pick up your own food.