Once in a while an airliner just up and disappears -- typically over ocean -- and lengthy and expensive search efforts have to be launched in order to find it. The most famous cases in recent years were of course AF447 and MH370.
It is hard for the bemused public to understand how something as large and technologically advanced as a wide-body jet can just go missing. Some people end up on websites like this one, asking why we can't just do such-and-such to make sure planes can always be found. The answers typically center around how such-and-such would actually be very expensive, and probably not 100% effective anyway. This doesn't really seem to convince most questioners, who wonder how important a bit of cash ought to be when there are lives at stake.
The purpose of this question is to clarify whether lives are actually at stake.
Suppose we had a magical technology which at negligible cost could give us reliable access to the exact flight path of an airliner in trouble anywhere on Earth. How much safer would that make flying?
For definiteness, let's assume that the magical technology gives us position samples at 1-minute intervals at a one-hour delay, so it won't be useful for real-time purposes such as ATC.