You missed the point. No one at the restaurant is getting a tip. The same person who would package up the food if you picked up in person (and who you would customarily tip) is the same person packaging up DoorDash orders, but with no incentive. The person getting tipped is the delivery service employee.
I am surprised that to-go orders are tipped in the first place.
Aren't waiters tipped because the law allows them to be paid below minimum wage?
AFAIK, behind the counter service people get paid commensurately, so tipping them doesn't make sense.
On the west coast waiters make minimum wage and there is still a tipping culture. Because of this, being a server or a waiter can be a very high paying job. To-go orders usually get tipped, but closer to 5-10% as opposed to the standard 15-20 for a sit down restaurant.