Since we are talking about genius ideas, where is the idea now? (Apologies if this was supposed to be obvious and I did not get it).
https://www.crunchbase.com/organization/deliveroo https://www.crunchbase.com/organization/just-eat https://www.crunchbase.com/organization/hungryhouse-co-uk
The original was http://waitersonwheels.com, which I used in the 1990's. It started as a catalog-based service, which waiter.com knocked off and improved.
It's not a defensible business model unless there's some exclusivity agreements with restaurants on the menu. (too tasty to resist.)
https://www.menulog.com.au/ https://www.deliveryhero.com.au/