Yes, this I know. I've seen the videos. Pretty sure some of them end up "poultry by product" This is my thinking though, say a hatchery has 1000 chicks. Expert sexer says 420 girls, 80 maybes and 500 boys. You get LOTS of orders for girls, and you can sell them a little bit higher than for straight run. You are filling an order for straight run, are you going to pull chicks out of the girls bin? Nope. I've never been to a hatchery, so I don't really know, this is just me, applying my logic to it. Also based on the number of posts where folks have bought straight run, and got a lot of cockerels. I'm sure there are still lots of leftover boys to go "elsewhere" Not talking about silkies and other hard to sex bantam types, or sex links. Just my guess, is all.
For straight run, the chicks are SUPPOSED to be pulled at random before the sexers get to them, then the pullets are pulled from the remainder and the males get ground.