statistics · cause
Survivorship bias
You are looking at the ones that lasted.
You only see the cases that survived. The ones that failed are missing, so the picture looks more successful than it really is.
Planes return with bullet holes in certain places. Where should you add armor?
The returning planes show where a plane can be hit and still fly home.
The planes that were hit in more critical places never returned, so those holes are invisible.
Reinforcing the areas that already have many holes on survivors protects the places that are least dangerous.
Survivorship bias is drawing conclusions only from the cases that made it through.