Death is 100% certain. ADLs can be subjective. That is why insurance companies have appeal processes in place and reserve the right to require a second doctors opinion if they doubt the first one.
Lets say someone falls and hurts their back.... one doctor might think they are unable to bathe and dress themselves... another doctor might not agree. Usually that will not happen, but it can.
Out of curiosity, do you have any stats or info about my original question?
Jack gave the perfect answer to your original question.