Wifework is a classic example of something that just falls to women as the norm. Obviously not in every single relationship but in the vast majority I know of including mine, men, even nice men, have very little awareness of how much admin and can-carrying and just being on top of things there is to be done, and that's a direct continuation of that situation in their parents' generation. Kids (both boys and girls) grow up seeing women just having to manage households while men swan off/laze about and they internalise that. It's also reflected everywhere, in ads, in the way people talk. "Oh men are no good at that stuff, chuckle!"
To change that, you have to stand up and push against the norm, you have to say "No I won't do all this, no, you can't help yourself to a lie-in or a weekend away whenever you fancy while I drudge, no, I won't sort out Xmas presents for your side of the family, and here is a big pile of school forms to fill in, bills to sort out, presents to obtain, kids parties to organise, holidays to book" etc etc etc etc etc. And doing that involves, in itself, stepping outside the role women are subtly pressured to occupy, of peacemaker, being nice, being amenable, being capable, being a "good mum".
When a woman does this it's quite likely that her DP/DH will be put out, think he's being put upon in relation to his peers, or it often happens that the MIL will not be happy with the wife shuffling some of that work onto him. Yes, you can split that fairly if you have a DP/DH who's ready and willing - they are not the norm.
And that's repeated a million times over in many other arenas of a woman's life - asking for fair pay, keeping her name, what have you. It's not just that the playing field isn't level to start with. It's that in pushing to make it level, you have to push, and be seen as pushy. That is so hard, many women won't even go there. It really is not as simple as "just make an agreement".