Fatigue is an issue most airlines are reluctant to address. You have to look no further than the intense lobbying of a weak regulator by just about every operator in this country!
Then there’s the destination. Served only by a 1930’s era instrument approach! I mean is it such a stretch for a potential new carrier to insist on a minimum level of navaids? Or do they risk the entire operation because of an unacceptable number of holes in the cheese?
These are by no means isolated circumstances. One day when the unthinkable happens, will the investigation trace the real cause back to the source? Somehow I doubt it.