As city dwellers we get a very skewed view of people's health and survival. Everyone we see around us is relatively well (or they wouldn't be at work, out shopping, eating out, etc). Except for a small number of family members we never see the people who are home bound or no longer alive.
When you live in a small town and know a lot of people of all ages you know that Mrs so and so died last week, Mary is poorly again, Jim is stuck at home since his stroke, the Joneses have a disabled child, and so on.
When you live in the city and mostly interact with people at your own work place, or who are out in public, you don't see the ones who aren't there. And if, like most people, you don't keep up with your classmates you won't know who has had a heart attack, who is very ill with cancer, or who has died. You don't even know about your own cohort.