As a father of two boys in their early/pre teens, I call bullshit. I have never heard of any movements to direct my kids into any fields that they don't naturally gravitate to. In fact at a recent high school meeting, I was encouraged to send my child to vo-tech since he doesn't seem to be interested in high school (he is doing poorly in English and Spanish, practically straight As in Algebra and Chemistry), but he's a boy, so he should go fix cars and do plumbing, not STEM, never STEM.
Perhaps you don't see the sexism because you don't have boys at that age, but as someone who does, and lives in a liberal state, I can see for sure that it happens against boys as much as for girls.