I think this plays a big part, we don't tend to care for our family members when they need it because of a variety of reasons.
Taking my own family, one set of grandparents lived around the corner, the other at the other end of the country, both my parents needed to work full time, all my aunt's and uncles worked full time and are scattered across the country due to work/opportunity, there was no one to care for my grandparents should they have needed it (only one GM went to a home and it was for short palliative care that needed nursing input) without big changes to be made, loss of income.
And that's before you get to families breaking up, single parent families, illness and money worries.
I did bits and pieces for my nan as she got older, shopping, cleaning, caring for her after falls etc, but I also had a young child and a ft job, I couldn't have cared for her full time if she had developed dementia for example - I was the best placed to do so because I was actually a dementia care assistant, but practically it couldn't have worked and we'd have all had a miserable time and my nan and DD quite likely at risk.
Both sets of GPs cared for their parents until they died, firstly in their own homes because they lived around the corner and then latterly, moving them into converted dining rooms, but, neither of my GMs worked, both GFs did - one an ambulance driver (before paramedics) and one in a 'professional' job which he got on merit and working up rather than academic qualification. But they could support the family on that one wage, with my GMs looking after their own children, grandchildren and their parents, I can remember taking sandwiches and tea into my great GM and all the children filing in on Christmas morning to see her.