The main reason why girls are not choosing STEM is because it doesn't intrest them as much. You can try to put the blame on anything you want, but that's reality.

I love technical things and am the father of 1 son and 3 girls. I of course would love to do technical things with all of them. With my son it's easy to get him excited about lego and such. With my girls? Well, maybe you should give it a try. I decided to play with my kids the things they like to play with. And with my girls it's (unfortunately for me) non technical things.

This preference is also highly documented in gender equal societies. So do us all a favor and stop talking bullshit while it's obvious why women don't select STEM: they don't want to.

PS: My oldest daughter is going to follow STEM next year. I'm happy, but mainly wish her to be happy. If she continues it, fine. If she decides she wants to do something else, also fine. She's good at math so that's the main reason she picked it.