It's extraordinarily complicated but I agree with @brightdawnfading that simply blaming women isn't very helpful. There are deep seated societal issues, social conditioning and expectations that are very hard to just buck off and change - for both men and women.
My DH is definitely one of the "good ones" but the reality is that he has had to actively LEARN how not to be an entitled wanker of a man because he was simply conditioned that way. And he is the first to acknowledge that he's had to actively work to change what seemed totally normal to him because of the 100000 messages boys and men get about what is "normal" or what they should do.
And many of these subtle messages, when women (or men for that matter) point them out, there's often defensiveness and backlash. For example, those campaigners who have tried to shine a light on the issues of clothing for girls vs clothing for boys - even at toddler age. 9/10 on MN, on Twitter, on other platforms when they point out the disparity in style, colours, messages, graphics etc, there are dozens of people coming on to say, "well, you don't have to buy that for your child" and similarly simplistic responses. And then of course, there's the far more extreme version when women stand up to say something about work or pay or whatever and they're shouted down, threatened etc.
And as others have pointed out, it's often worse with children. So even when a woman knows perfectly well that the set up isn't fair or right, her choice is to let her children suffer or to step up and do it herself.... so she just steps up and does it herself. And don't even get me started on the way single mothers are treated vs single fathers....
Meanwhile, those societal norms and standards I mentioned cover everything from the way women are expected to behave to the types of jobs (and earning potential). Plus workplace assumptions about childcare and commitment etc.
Example - a man who is the lower earner, perhaps working in a shop or as a shift worker with a partner in an high paying office job - when the DC are sick, he can't possibly take work off "people are relying on me, I'll get fired etc." When it's the other way round, she must take work off because, "your job is less important to us as a family." I've seen this 10000 times.