Watched an interesting documentary on PBS called Innovations and it talked about airline crashes and about NTSB recommendations that were acted upon or not by the FAA.
A number that interested me was the number $2.5 million per passenger-deaths when calculating break even of when safety recommendations are implemented or not. This number was uttered by a US government aviation official (FAA or NTSB).
In other words if the new technology costs cannot overcome this number then it doesn't have to be implemented by industry.
I've seen a similar documentary years ago but I can't remember the $$$ break even number for safety improvements.