People keep saying "we" are built differently but when it comes to the bicycle cycling motion I'd like to hear what you think is so different! It's like when they said women had to ride horses sidesaddle because we have such enormous thighs a straddle saddle would be too uncomfortable LOL.
Basically gender different are small, average not dichotomous and do not matter a damn for the ergonomics of cycling. Men and women can use so called male and female models interchangeably. For most of my life I used models for men that were handled down to me by siblings.
The step through frame relates to clothing only and I doubt many women these days are biking with ankle length skrts and voluminous petticoats, and an absolute prohobition against allowing a man on the street see one's stockinged ankle.
In terms of getting from here to there, the so called mens and womens bikes are the same. The pedals are the same, the ratio acheivable between the seat, handles and pedal are the same (when comparing people fo the same height), the moving parts are the same, the materials are the same.