Maybe the answer is “they have to teach it to someone”. Just kidding. You bring up a very good question and one that should be brought up to Torah Umesorah. Why are you stressing our girls out so much? Why are you bearing down on them so hard and teaching them things that boys never learn and it is NOT their job to know.
The girls are trained to be smarter and smarter and then the boys they date can’t hold an intelligent conversation with them. Every year they come up with more and more ideas of what to teach the girls. Every single year they raise the bar on the girls. Every single school tries to outdo the next. They try to outsmart, outfrum and outbuild each other to the detriment of the kids. They just refuse to allow kids to be kids.