Women get paid less than men for doing the same work, across all industries. Pay them the same and the "confusion" will diminish.
When you average all women and all men, you get a "gap". However, like the imbalance in fields, this is almost entirely due to different choices. When you control for factors such as field, hours worked, years worked the gap effectively disappears.
Choices made by women are influenced by the glass ceiling, society expectations that women will take care of children and the elderly, and the traditional fields where they're expected to work. The decision to measure the gender gap by comparing equal working hours and equal job positions is not innocent, is itself a politically motivated and comforting way to make rational people think "I told you, there's nothing to see here". You need to evaluate what causes women to have those less hours in less paying jobs, to see whether there's discrimination or not.
Yet the salary wages discrimination reappears when you factor in hours dedicated to domestic work (the "second shift"), differences in salary between fields with equal risks (exposition to chemicals, hardship) where workers are majority women vs those with more men, or companies' (irrational) tendency to default in promoting male workers over females in similar situations.
https://www.washingtonpost.com/graphics/2017/business/women-...
It is seen in human beings and animals that statistically females mate sidewards or upwards in terms of providability. This in turn applies a pressure on males to compete for more and accumulate more resources, whereas females are not measured by males on their providability hence have no pressure on them to fight for the same resources. So, men will always compete more to get a greater share of the pie, this combined with capitalism explains whatever income gap remains after attaining equality of opportunity. Shouldn't the underlying metrics of mating preferences also be taken into account before putting it all under male sexism and patriarch umbrella ?
You can't ignore that we come from a culture with a tradition of 60+ centuries of male-favouring sexism and patriarchy, which has not vanished merely because of a theoretical solution to it (legal equality) has been formally declared. There's a lot of social inertia introducing biases in the opportunities available to women.
You can take into account mating preferences all you want, but how do those affect choices of job positions other than very indirectly? On the other hand, irrational prejudices in recruitment and career advancement processes have a direct impact on the quality of job positions that women have access to, and therefore in their opportunities. Unless you're downright denying that such prejudices exist, this cultural factor would have a larger influence than biology.
The incentive models, which take data from both biology and culture, claims a prediction that as you measure equality of opportunity and compare nations it will correlate to inverse gender segregation in the work force. The more equality of opportunity the higher gender segregation will be, caused by incentives that is derived from gender roles, sexual strategies, and sexual dimorphism.
The prejudices model make the opposite prediction. It claims that when measuring the equality of opportunity the higher it is the lower the gender segregation should be.
In order to resolve the question one measure equality of opportunity and gender segregation, creating data. This create a scientific valid argument in favor of one model over the other.
That is one aspect of the theory. An other aspect would be to measure difference in prejudices between different professions. If the model is correct then it should be able to predict based on such measure which professions are gender segregated and which are not, and inversely predict the level of prejudices exist per profession given any country. The incentive model claim that incentives are a large influence and such you could not make a predictive model based on measuring prejudices.
The incentive model also predict that nation where the incentives are different (based on Maslow's hierarchy of needs), you should see a correlated change in gender segregation. Incentives such as reproduction is listed last among the physiological need, so nations where water and food is scare for women should result in higher incentive to seek professions where those are easier achievable. The prejudices model would argue that there is no such correlation.
This is of course just a small sample in order to scientifically evaluate the two different theories. There is also matching philosophy theories (their names escape me right now), arguing in different direction to explain the data.