>>12136831
It can be a huge pain in the ass for a small business thats not trying to change its whole operation.
By upcharging you can guarantee any added volume is worth the trouble, while discouraging the volume from overflowing current operations structure (no need for extra staff or changes to floorplan).
Some restaurants get 50% or more of their business through doordash, and it changes their operations a lot. They may need to redesign the menu, devote a section of the restaurant to assembling bags, and appoint new staff to deal exclusively with delivery.