First things first: Gaetano Perugini, engineering adviser at Aviointeriors, is keen to stress that the concept's not about creating "cattle class" and cramming in as many passengers in as possible.
The Skyrider takes up way less space than the average economy seat -- just 23 inches -- so the idea is airlines could cram in their economy seats, and still allow other passengers to book other kinds of tickets on the same flight.
Even Perugini acknowledges it's not necessarily an enjoyable experience, but he reckons for short haul, say a brief hop across Europe, it might work.

Full article: https://www.nowscience.co.uk/single-post/2019/04/03/The-Future-of-Air-Travel-Could-Include-Ultra-Economy-Class-Seating