You seem to be asking why you don't see this directly in the data, with a number going down. But you do realize the the number of drivers and miles driven have both increased in that timeframe, right? Such that, if the safety had remained the same, the number of incidents would have gone up. Pretty much by definition, that means a number remaining the same means something kept it from growing.
https://www.aarp.org/auto/driver-safety/dangerous-reliance-c...
Reading your link appears to be more fear and caution than data showing things are worse? There is a broken link that ostensibly looks at lane assist and how it can have problems in bad weather. But nothing that says rear view cameras actively cause trouble? Just a fair callout that you shouldn't exclusively rely on them.
https://www-fars.nhtsa.dot.gov/People/PeoplePedestrians.aspx
Your dad's argument about seatbelts is that it will make people worse drivers. My argument is that backup cameras don't reduce fatalities because there are few to begin with, involve low speeds, and the data hasn't show any real improvement.
The point, if you want to save lives, let's start where the biggest savings are. Those are better driving testing and education (I do support these) and breathalyzer interlock devices (support these for offenders, not universal).