So we are saying because academia is so utterly badly paid you cannot even afford a live in au pair at £60 a week or 3 hours after school care at £10 a hour in the week
According to a quick google, research council PhD stipends in the UK are £13,726 pa (tax free), which is a good guess as to what the average PhD student lives on. The average postdoc salary in in the range £23,475 - £35,254. So, with a PhD and 2x2 year postdocs, you will get to around 30 years of age on a salary that's not great, probably have no savings because you'll have had some period of self-funding and had to cover early years childcare and other expenses such as travel that you didn't get university funding for. Plus the best universities tend to be in expensive cities so your salary doesn't go as far as it might if you had freedom over where you live.
So yes, a live-in au pair or £150 a week on wrap around care can be hard to cover.
and because these women are in very unequal marriages where the man insists if anyone collects children from school it must be the woman
Not necessarily, most academic couples I know share duties. e.g. my DH and I split pick-up and drop-off, although our DD is only 2 so is at nursery all day long and we don't have to deal with early school finishes. This week, in fact, the nursery rang to say that DD was ill. I had a meeting scheduled so DH took the afternoon off. Even so, having to deal with half of the childcare stuff can be a hinderance (but I think academia offers a lot of flexibility to deal with this - one thing in its favour!)
that is why these women find it hard and because they married men who earned very little too?
I think this is a big problem for female academics, who often marry male academics. Male academics are often married to women who are prepared to stay home and do the domestic stuff.