Sure, but you could always do that and be delivery-only without paying anyone. I think the service you're getting here is primarily the exposure of being on a popular platform.
That and them handling the order process.
That and them handling the order process.
Which means they might order less food than they would have with lower prices. Or that they might decide it's too expensive, and order from another restaurant.
Ok so if that's an option then what's the problem?! I don't get the fury here.
Restaurants are free to partner with delivery companies.
Restaurants are free to not partner with delivery companies.
Delivery companies are free to buy and resell product from restaurants and add their own markup.
Restaurants are free to decline to sell product to delivery companies who add their own markup.
Everyone can do what they want here.
Which is fine. I think the problem is that they are representing themselves as if they are the restaurant, not a reseller. Customers might go to the website the delivery company setup (restaurant-name-location.com instead of restaurant-name.com or whatever their pattern is) instead of the restaurant's website, see the high prices, and decide to try a cheaper place.
That's exactly my point - and your last touch is the Deliveroo worker. So take it up with them. They can then take it up with the restaurant if it was the restaurant's fault, but that's their job as the reseller.