Generally, they inflate prices (or take some % from the restaurant, so the restaurant has to increase prices).

And have a small delivery fee.

And have a small “city wants DoorDash to pay its workers fairly, so it’ll charge you an arbitrary amount extra” fee

And a bag fee.

And sales tax.

And a tip

Oh and don’t forget the service fee.

I’m not kidding, this is from a recent receipt. There are 6 fees PLUS the cost of the actual food.

Other delivery platforms are similar