As an exercise, go to any local store that sells items for children. This includes stationery, school supplies, coloring books and the like.
And see how many of them market “super heroes” like Superman, Batman, Spiderman, The Incredible Hulk, and Iron Man. These four heroes, being the brands that they are, can be found on just about everything. At least, things that are marketed to young boys, that is.
Now, look at what is marketed to young girls. You will not find any equivalency. The closest you may get is the Superman shield in pink (to market as Supergirl), but that is it. Young girls who like superheroes will rarely find Wonder Woman merchandise. No lunch box will be found on the shelf of most of these stores. Same for T-Shirts.
Want a Wonder Woman book bag for your child? Forget it. But you can find bookbags any of the four heroes mentioned previous in any retail outlet. Most merchandise regarding Wonder Woman for kids might be found on the net through specialty shops. But these are not easily obtainable.
What this speaks to is how heroes, heroines, and heroism is marketed to children. Boys are steered into roles like Superman and Spiderman, but girls don’t get to see Wonder Woman, She-Hulk, or Storm unless they go to a comic book shop or watch a video – and even then their heroism is limited.
This is the self-sustaining black hole of thought: Wonder Woman and other female heroes have little traction because there is very little “seed planting” in the younger generations. Thus, female heroes will be seen more as outliers than anything else.