I think it's much more complex than money or will/laziness. Sometimes, it's the mother's subtle power manoeuvre to gain or maintain status in the household. I'm talking mostly about cases where (1) it's a nuclear family where both the mother and the father want to stay together, and/or (2) both parents had high-paying careers before having children.
For example, the father may earn enough to cover the whole family (and more than the mother does), and/or they may collectively decide that "mum is better at childcare than dad". The mother then decides not to work. The justification on the surface is that it makes more sense money-wise than outsourcing childcare, especially if the children are young. And more people can empathise with the desire to raise your kids than to work for some corporation.
But once the decision has been made, the mother can then secure her unique position in the relationship, for at least the 20 years when children are dependent on them. First, the father will never quit his job for at least these 20 years, because the whole family depends on him. This is way more dependable than benefits, and often much more money. Second, the mother, delusional or not, believes that this can enforce the father's loyalty to her because "she's given up her career for the family." It's actually a way to increase her bargaining power should a breakup or divorce happens.
Not saying that the mother doesn't love her kids or love spending time with them, but it's not in conflict of her using them either, especially if she knows that the father will do anything for them.
I say this because I'm the child in this case. It's really a reflection of the mother's self-misogyny (believing that she has more value being a mother/wife, than working, even if it's a high-paying career), and actual misogyny, when it actually works out for the reasons I listed.
Sadly, many mothers' "plans" don't work out, and the father still leaves or cheats, and/or what you do for your children does not guarantee any returns from them. I maintain that women must work, no matter how painful it is at the moment, for their own sakes. Because the perceived easiness (and satisfaction of child-rearing) at the moment can quickly dissipate and you'll be left with 30+ years of uncertainty.