Could you provide me with the study which supports this percentage, to be honest, I think myself that 90% of the people will think that 18$ per hour is definitely too expensive. For example in an average city in Asia or in South America, this will be too expensive for most people, that's the reason why airports have not covered this themselves.
It is in the
Whitepaper on page 5, same as the other percentage with all sources included. Also that information is public on home page of the website:
https://air-pod.io/.