The concepts which cover the ground being argued over are societal risk and scale aversion, which basically deal with the idea that over a given period we are much more comfortable with 100 deaths in 100 separate incidents than we are with 100 deaths in one incident, irrespective of first/second/third-party status. The HSE published a summary of sociological research
here and concluded that "it is neither practical nor sensible to attempt to measure [scale aversion] in mathematical terms". This is why the eminently sensible road safety measures advocated by Tourist have not been seriously considered.
It is not just aviation that labours under the burden of societal risk - our railways are over-engineered and under-utilised as a consequence of it, and nuclear power likewise...