It’s complex and a lot of it is about structural sexism in UK society at heart I would say. I would add that you seem to only be looking at the situation from a financial perspective. For many people (and probably more women than men ?due to how we have been socialised culturally ?due to biological hormonal bonding with our children etc), big life decisions are not made with reference to finances alone. Some may prioritise spendings time with children and/or other family, caring responsibilities withthin the family etc, or even simply a less stressful exhausting having-it-all type lifestyle (especially after seeing our mother’s generation struggle, suffer and fail with that trope, plus some of us feeling deep down if we are honest with ourselves that we would have much preferred our mothers to be home more and at work less, however understanding we can be that they were smashing glass ceilings which was important and did not have the options that some of us have today of part time work etc. thanks to their efforts).
Some of us got really ill as a direct result of being female (I ended up sectioned for months due to puerperal psychosis and was then diagnosed with bipolar disorder which like most mental health conditions, affects far more women than men), and that limits earning capacity and fitness to work full time and put ourselves in the high stress and long hours and high responsibility situations and roles that tend to pay well.
I will also say here that I was very limited in both my earning capacity and ability to “make” my partner take on a fair share of the work after having children by domestic abuse, something that as in my case, often becomes evident only after pregnancy or childbirth. My husband promised me the world and I stupidly believed him as he kept up the facade long enough for me to marry him and have a child with him and then I was (relatively) trapped. And as much as others might point and laugh and say it’s my own stupid fault for marrying such an awful man in the first place, you have to understand that the man he really was was not the man he portrayed himself to me to be. My whole family and all my friends also thought he was this great guy and have all been absolutely horrified at how it all turned out. And I’m not sure any of that is my fault actually. I’ll never forget one friend seeing how my ex rated me soon after childbirth saying to me “but why do you let him treat you like that?” I didn’t “let him” any more than any women “let’s thmemselves” be raped. Nobody can control another person’s actions or words, all you can do is break ties and walk away which I ultimately did but most of you can surely understand how difficult that is a few days postnatally.
So now here I am, a single mother with bipolar disorder and an abusive ex who is constantly taking me to court over child custody (because oh yes the family courts are also structurally sexist in my opinion when it comes to how they deal with women and children who have been the victims of domestic abuse). All of those things put me at a financial disadvantage, and all of them are intimately linked to being female.
i have been the higher earner in a relationship more than once and let me tell you, many men, particularly the “alpha male” type absolutely hate this dynamic, they feel consciously or otherwise that it emasculates then I think, and it can breed serious resentment. I don’t think it should be this way but I think there is little doubt that men’s role in UK society is changing fast and I think men do feel generally under threat, that women don’t really need them any more. Among my friends I can’t help but observe that separation and divorce tends to happen when the woman outperforms the man financially, and couples where the woman earn less tend to be much happier and more settled. For this reason having loved this experience more than once, I would much prefer that any future partner earns more than I do.
Having said all of that, I will also say that I would be in a hugely worse situation financially than I am now had I not studied hard and taken the opportunities that I am privileged to have had in life to establish myself in a relatively high-earning career which allows me to work part time (and therefore protect my mental health, spend time with my child which is super important to me, have some semblance of a social life, deal with constantly being dragged to court, and pursue other non work-related interests). And I’m very glad I did so and part of it was motivated by wise older women advising me as a teenager to make sure that I was never reliant on a man financially.
Ultimately however, give me the fortunate position of a really solid marriage with a decent man earning well who was happy for me to stay at home and take care of our children, and I would have jumped at the chance to do that despite it not being financially the best option for me. I think the role of wife and mother is very important and valuable and I would have loved to have been freed from what I see as the shackles of having to earn a living to be able to devote myself to that wholeheartedly. I think I would have found it incredibly fulfilling. It wasn’t to be for me but I don’t understand why some women find it hard to understand why something women would choose this path if it’s an option for them.
I hear what you are saying about there being value in continuing to work in the longer term even if you are only paying your salary straight over to childcare but you have to understand how demoralising that feels surely? Plus for many women it’s not even that but putting yourself in a position where you actually have less money in your pocket at the end of the month by going to work, and not only having to juggle all of the stresses and responsibilities of being a working mother, but also losing important time with your child and handing them to someone else who will see their first steps, first words, attend their nativity plays etc. It’s valid for some women to feel that if the money is all the same either way they’d rather raise their child themselves than outsource a lot of that to someone else. I remember my own glass ceiling breaking feminist mother being horribly upset at one point when my younger sister started asking for our nanny rather than her when she was upset about something.