Because we couldn’t possibly have both a boy and a girl playing Ninja Turtles.
I know this is far from news, but I looked through the whole thing. 2-page spread of “create and explore” that was basically crafts and only featured girls. Followed by a spread of “eduscience” that was actual exploration and only showed boys. Not to mention that a solid 2/3 of the book is color-coded blue=boy, pink=girl, so you don’t even have to look at the page to know if it’s for you or not. 4 pages for Lego and other building toys, with a fair bit of space devoted to the kids (as well as the toys), and they’re all boys. Lego Friends has its own page, showing only girls, and sharing a spread with toddler building toys.