Street signs are a reflection of society. In older cities, like the European ones listed, for centuries society was male dominated. All of the famous people, both locally and nationally, were men. That a street might be named after predominantly men is not a surprise.
Looking at Rome, a very old city by anyones standards, slightly less than half the streets are named after people. I will bet the mayors wife is right. In the early centuries they named a lot of streets after famous people. Mostly men. The fact reflects the society.
An interesting study would be to narrow the scope to just the streets named since 1960.
Is the percentage named after women different than the long term trend? Break out the naming delta by decade up to the current day and see what the current trend looks like. Is there still a bias in naming or has the tide changed in recent times?