The problem with CAC in this market is that I doubt enough people say, "I'm hungry, I'll open door dash". Instead I want to eat from a local restaurant whom I call for delivery and then door dash pays someone to bring my food. In that case DD hasn't "acquired" me as a customer.
Yep... I use whatever one offers me the best deal. These days, I rather order it from the restaurant directly if they have curb side pick up. It's better for them and me. Delivery drivers often get lost or are incredibly late.