A bar chart titled "Deaths from Wars & Cars" the Leftmost bar is WW2 at 78M, followed by Cars 72M, Mongols 39M, Taiping 25M, Ming Qing 25M, 2nd CN-JP 20M, and finally WW1 19M. A note at the bottom states "Showing estimate midpoints"
There isn't something like "death from old age", everyone dies because of something, like a cardiac arrest, organ dysfunction or an undiscovered tumor.
That is at best a hypothesis, though I agree with you. Until we start really caring about death and doing proper autopsies, we can't be sure. Today, there are still a lot of death certificates where the cause of death is listed as "dude just old".
Because it doesn't matter. Wasting time on finding out if grandma had a tumor, cardiac arrest, organ failure, or a seizure ultimately doesn't matter because if it wasn't X, it would've been Y, or Z. The organs don't grow back the same quality, and it detotiates every time, so at some point you are frail, and all your organs are failing, and it's gonna get you sooner or later.
Wasting manpower to find it out for statistics sake is just plain dumb. Also nobody wants doctors to cut their 90 year old gramps just for the sake of statistics.
I understand that more time with your relatives is always a plus, but not everyone is enjoying life climbing down a flight of stairs for 15 minutes, taking 5 different meds every day, and fearing everying illness having you go to the hospital. Life is not always enjoyable when old, and keeping grandpa on life support could be viewed as cruel from them. Speaking from experience.
People are working on it. A good start is trying to live as long as you can. I would advise avoiding sugar, processed food.
I found a video interview of someone aged 82 who looked and moved like someone less than half that age. A beef farmer. They seem on the right track. They don't eat anything they don't grow or hunt