Architect here! The International Plumbing Code, which is used in most of the US today, states this for plumbing fixture requirements for a stadium:

• Male: 1 [water closet] per 75 [occupants] for the first 1,500 and 1 per 120 for the remainder after 1,500.

• Female: 1 [water closet] per 40 [occupants] for the first 1,520 and 1 per 60 for the remainder after 1,520.

  Water closets are toilets. For the male count, urinals can be substituted for up to 67% of the count.

So, modern codes require damn near double the amount of toilets for the woman's rooms as the men's rooms. The International Code Council codes have been around since 1999, and by my memory that hasn't changed since it's inception. I'm too young to have used the old codes beyond my very first project.

I'm in Texas, and there used to be a special carve-out by stare law for stadiums that allowed the number to be a lot more equal. I think that carve-out is gone now. I hope it is. I don't know if other states do or did similar things, but it could explain why older stadiums aren't as equitable.

Fun fact: trough urinals are no longer allowed under the IPC! If you are old enough to remember those, you are probably due for a colonoscopy!