That’s not enteirly true. In London all my favourite places are only on Deliveroo, and not on Uber Eats (at least in my area). Maybe the have some kind of exclusive contracts?
I find that the Deliveroo prices are heavily inflated for some of my favorite places. And that the info number listed in a restaurant's info page allows one to call the restaurant directly and order the same food for significantly less.
It used to be this way in Paris as well until it wasn't, now almost all these restaurants are on Uber as well. It seems Eats can just pulverize these deals anytime they decide so.
Well somebody else's favorite places are on Uber Eats and not on Deliveroo then ;)