Unrelated to Deliveroo, but "How to Become TripAdvisor’s #1 Fake Restaurant" (2018) was very telling as well: https://www.youtube.com/watch?v=bqPARIKHbN8

From the video description:

> The Shed at Dulwich was the number one rated restaurant in London, with foodies, celebrities and bloggers trying to get a table. The main obstacle for them, however, was that it didn't exist. Over the course of 8 months VICE's Oobah Butler used an assault of fake reviews to get his 'restaurant' to the hallowed top spot on TripAdvisor.