If you take your point to its logical conclusion, every risky activity would need to be quantified prior to any individual accepting participation.
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I'm not trying to be trite, only saying that its bloody hard to come up with an acceptable measuring stick that truly informs the participant of either the absolute risk or the relative risk.
I agree completely!
Your argument supports the logical conclusion I have already stated:
Nobody - but nobody - understands the probabilities of each and every one of the bad things that could happen to or on an aircraft, happening.
The suggesting that participants accept the risks of an activity is a fiction.