What is safer? 10,000 penalty notices issued or Zero penalty notices issued?
accidents / incidents per thousand hours is the only true measure.
as for cost benefit analysis, there is plenty of published methodology for that.
what for example, is the point of me fitting ADS-B? I thought about a GTN650 as a certified nav source with a Garmin 330 transponder. AhHa! I thought, little Sunfish will be plainly visible to all and sundry and ATC will smooth my path for me on occasion.
Then I realised that all I was doing was fitting an automatic infringement generator with zero safety benefit to me personally. A simple ADSB feed to CASA from Airservices and CASA is alerted my flying and can track my every move in real, or pseudo real, time.
And I still don't see why a GA VFR aircraft needs a certified ($8000) GPS when we are not supposed to be anywhere near big jets, and in any case the ADSB message has a quality of fix field that can be set to a lesser value then certified GPS anyway.
Then of course there is the barbed hook that once its fitted, it must be used and if it fails you have only three days grace to fix it.