Do even those mothers who are responsible and provide care for their children treat them as equals?
Of course they don't.
Yes, according to this survey majority of mothers treat their sons better than their daughters (I experienced this first-hand from my own mother):
theguardian.com/society/2010/oct/06/most-mums-favour-sons-survey
That's wrong though and stems from those mothers being raised in a patriarchal society.
Such women only care for their children as a longterm investment for their own benefit
That depends on a particular individual. There are women
and men who are like that, but there are many others (women and men) who aren't like that.
they know they will send their husbands to an early grave
A quote from a Polish article on WP abcZdrowie titled "Polish men live 8 years shorter than Polish women. National Health Fund is giving causes.":
"
5. Men who are in a relationship are healthierScientists from Harvard Medical School have proven that
men who are in relationships are healthier (especially if they're married), they are three times less likely to develop cardiovascular diseases and they live longer. The partner's role can't be underestimated also in Poland. The portal uPacjenta has conducted a poll which results show that:
- men in relationships are more convinced about the necessity of preventive examinations: 80% of them think they're necessary (only 60% of single men think the same),
- 25% of men declare that they're usually being reminded about examinations by their other half."
they will still need someone around to take over his responsibilities of providing for her.
In Poland women have retirement pensions (if they worked) or so called family pensions (if they were housewives and didn't work).