I know that DoorDash specifically also raises the price of individual menu items by a $1 or $2 sometimes compared to paying the restaurant's menu price directly.
I've noticed higher costs too, but wondered if it had to do with having to order items separately instead of as a meal. For example, ordering a sandwich, fries, and drink, instead of a combo with the same thing.
When I found it, it was for a place called Ike's in the Bay Area. All of the individual sandwich prices were $1-$2 more than if you ordered directly from the Ike's app. It wasn't because of a combo price reduction or anything. (And funnily enough, Ike's uses DoorDash's white label delivery service to actually deliver the food.)
I stopped using Grubhub for pickup because the restaurants would consistently raise their prices on the app to make up for Grubhub's prohibitively expensive fee.
So THATS why the prices are more expensive! I don’t use Uber eats or grub hub because of this lack of transparency. I figured the app was increasing food prices and then charging me for delivery and a tip