Diamond princess was tested early and often and therefore able to get immediate quality care before medical systems were overwhelmed. This gives something like the ideal minimum fatality rate if, for the most part, everything goes right with detection & treatment.
Out in the wild, this is very much not the case. Testing it still thin on the ground in many locales and the pressure exerted on the medical infrastructure is not evenly distributed, making levels of care vastly different.
Think of it like a highly treatable form of cancer: If everything goes right and it's caught in early stage 1, fatalities rates are much lower than when it's only detected after reaching stage 4 and fatality rates are much higher.
Diamond Princess, for distinct demographic group only, represents detection at Stage 1.
Out in the wild, this is very much not the case. Testing it still thin on the ground in many locales and the pressure exerted on the medical infrastructure is not evenly distributed, making levels of care vastly different.
Think of it like a highly treatable form of cancer: If everything goes right and it's caught in early stage 1, fatalities rates are much lower than when it's only detected after reaching stage 4 and fatality rates are much higher.
Diamond Princess, for distinct demographic group only, represents detection at Stage 1.