In our world, human population groups evolved in isolation for one hundred thousand years[0]. And at least as measured, the difference between the lowest and highest IQ groups is about 35 points.[1]
Men and women are closer in many respects, but it depends on the arena. Men still have double the upper body strength that women do and about seven times the testosterone. When you're talking about anything physical, it's impossible to treat men and women the same (speaking in terms of group outcomes).
And even in the psychological realm where there's a lot of overlap in trait distributions - even small differences that produce a 6:4 ratio around the average, as many gender differences do, become absolutely massive at the edge of the bell curve - like 50:1. And the nature of our modern world is that it's at the edge of the curve where the big results are made - the very smartest physicists, the most capable engineers, the most dedicates CEOs are who are driving outcomes.
Far from making egalatarianism easy or even, it seems like the way our world is set up makes it simply impossible.
It might even be easier if the differences were bigger! They'd be impossible to deny and we'd just learn to cope with that. Right now we're in a weird place where the differences are huge and impactful, but there are just enough individual exceptions and just enough fuzziness to deny that they exist at all.
I think we need some ethical framework that can be moral and evenhanded and kind without having to pretend that distinct groups are the same; a morality based on false beliefs about the physical world cannot stand.
[0] The last common ancestry between the San people from southern Africa and Eurasians was roughly 100,000 thousand years ago. For Australian Aborigines, it's about 70,000 years. For the larger sub-Saharan African populations, it's about 50,000 years. In contrast, Chihuahuas and Bernese mountain dogs have perhaps 3,000 years of separation.
[1] Obviously some of this is environmental, but the scientific consensus seems to be that a good chunk of it probably is not.