It still blows my mind that in the 80’s being 53 (Blanche) qualified you as geriatric, “golden years”, age. 53 year old ladies today would absolutely scandalize 80’s Blanche and 90’s Samantha (even though she was in her 40’s).
If I recall correctly, there were a bunch of advances in medicine, especially in relation to heart problems, in the 1970s, so the long-term effects of that had not been seen yet.
Prior to antiobiotics in the early 1900s, between war and disease, life expectancy was less stable. It stabilized post-war and antibiotics, but then there’s another spike in the 70s. So they were still used to a world where 50 was 20 year until average lifespan death, not 30 years, it’s literally a whole ass extra decade. Also our understanding of health has grown, people have stopped smoking and drinking so much.
Anyway, I think they all lived in a world that life expectancy had been and mostly was stable and the benefits of medical solutions being developed in the 10 years before that just hadn’t been around long to manifest that extra decade of life into existence.