Also, how often do airlines suffer depressurization with extended high altitude flight, where some failed masks would result in detectable injury to passengers? Luckily very rarely, as most incidents result in immediate expeditious descent to breathable atmosphere, where in such an event a lack of functioning mask would almost be undetectable and its use practically unnecessary
Why bother to have slides? Or any other emergency equipment for 'rare events'? Would you care to tell us the duration of consciousness in the case of sudden depressurisation in the cruise for a healthy adult? And would you care to postulate on how long an elderly patient with heart disease would survive? And compare it with the time needed for an emergency descent to 10,000 feet?
Not sure I would be happy without oxygen. Must pick one of the 75% of seats that has working oxygen. Ryannair would probably be charging a premium for them if they operated them