Sorry, quote fail. In response to "honour your parents and live in god's earth":
Lots of people aren't religious, for one thing.
Lots more see comments like that as convenient for the state to use to try to guilt trip people into being unpaid carers.
But people have more hours to work now than they used to. There's no SAHP unless you're rich. There's only a fixed amount of hours in the day, people can't use them twice and to try just leads to the carer becoming chronically ill too. Which helps nobody and solves nothing, only adding to the problem.
I'd say those are the main factors these days.
Also nobody lives nearby any more. A lot easier to do ad-hoc caring when you only live next door or a few streets away.
And people didn't linger like they do now. They were healthy and mostly capable until they got ill and died. Not lived seemingly forever in an increasingly frail body that was never designed to go on this long, being constantly patched up by modern medicine but never actually healthy, thriving or having quality of life.
People looked after their parents in the days when their own DC actually left home in adulthood (late teens/early 20's) so there was space.
With no state care the parents were, I expect, more grateful for family care and didn't bitch and moan and dig their heels in about having to leave their home and about how their DD/DIL (because let's face it, it would have 99% been women doing the caring) did things differently. Or if the parents did complain, the women carers sucked it up, having been trained from birth to expect to skivvy after others until they died or became infirm themselves. No expectations of anything different, of equality, of a life of their own at all. Family carers now won't tolerate being treated like servants by their infirm relatives.
Parents didn't used to worry that their little ones would get run over because there were far fewer cars or that their teens would get sucked into county lines gangs because they didn't exist.
When nobody moved too far away everyone knew everyone else, that's where "the village" to raise DC came from. And even troublesome people didn't "shit on their on doorstep" if they had any sense. Now people mostly don't know their neighbours and there's no sense of community.
It added up to DC being able to be outside the home more safely, entertaining each other and not getting under mum's feet whilst she cared for elderly relatives. Not stuck in front of a screen or needing attention every 5min, until they're about 30.
It's a different life now and expectations about care have had to change. It works both ways. Few grandparents are raising DGC whilst the children's parents work, even if it's a single parent household and where they are helping, the children's parents aren't necessarily grateful for the help but want to treat the DGP like staff. Don't forget the DGP are often still working when DGC come along too.
There's more awareness of the harm caused to DC by emotional abuse etc, and to the elderly by improper care practices that amount to some form of neglect, and to the carer in the form of bad backs and emotional burnout etc. People are taught from birth to (hopefully!) value themselves and their well-being and they're taught to expect good health and to expect to be able to enjoy life. Not to run themselves ragged with no end in sight. Even some branches of the state encourages us to put ourselves first and remain our healthiest, so as not to become a burden on it, whilst simultaneously telling us to work all hours. It's difficult enough to achieve both of those, especially whilst DC are young without adding caring for a disabled (or just plain ancient) person on top.
Times have changed, it's as simple as that.