And yet, how many accidents and fatalities actually happen each year and how many of those are related to the engine?
Considering the number of hours flown - precious few.
Yes singles are cheaper to run, but if they were being wrecked often and crew lost then it would rapidly become more expensive for the operators.
It is the nature of any commercial venture to only change once cost justifies it.
The reality of risk, in this environment, is that it extends far beyond engine reliability.
There are trade-offs in every environment and safety is never first, more often it is a strong third.
!00% safety does not exist, and if it were the absolute requirement, no one would ever venture outdoors.