In that interview, I talked about how low cost airlines had unbundled all the components of a flight ticket, and instead of charging one all-inclusive price, they had taken to charging for everything they could (meals, inflight entertainment, baggage, etc...collectively known these days as 'ancilliary revenues').
I also hypothesised about how long it would be before the airlines started to charge customers to use the aircraft toilet.
It now seems that others are starting to ask the same question. Sarah Maxwell's book, "The Price is Wrong", contains a forward by Jon Luther, who is the Chairman and CEO of Bunkin' Brands Inc. In his forward, he asks the very same question.
Even though my original hypothesis suggested the airlines were unsure whether to charge by weight or time, I still believe it is not beyond the realms of possibility that this may happen at some point. I was recently told that it costs about $1,000 to flush an aircraft toilet. I'm not sure how true this is, but what is clear is that aircraft toilets are very high tech.