Sunfish,
Just to highlight a point, about perceptions and facts etc.....
Best example I am aware of is ABS in cars, has it reduced the frequency of nose to tail crashes? Apparently not, because drivers compensate for better brakes by driving closer together.
The reason for this is simple, they may not have better brakes at all. ABS contrary to what many people think, does not make the brakes stop the vehicle any quicker, it just prevents you from over braking, locking a wheel and having reduced control. In some instances it can actually increase stopping distance.
It is as you point out, a way of shifting risk, and catering for drivers who who have lesser skills.
J
