Compared to the past we have massively reduced the carnage on our roads .
Generally drivers are nowadays much more clued in than they were in the past and roads are better engineered for safety .
The increased motorway infrastructure has made a big difference, with collisions three times more likely on rural national roads for a given distance traveled.
Also car safety features have improved significantly as well. What new car doesn't come with a proliferation of air bags, and features like improved crumple zones, emergency brake assist, lane departure & blind spot warnings, etc..
I also wonder whether the increased volume of traffic has had an affect also. Particularly in the busy commuter areas, with increased grid-lock leading to lower speeds.