Regarding the picture of the broccoli floret, that looks like a live caterpillar and fresh broccoli.
What are the chances of EVER finding a live caterpillar clinging to a floret from commercially-packaged frozen broccoli?
How would it survive?
And if not, what is the relevance of the picture?
And, while the illustration of frozen cauliflower does show a thrips, what is the case with something like kale? How likely would it be to find thrips in commercially frozen kale, after it has been commercially power-washed?
I am asking because I wonder whether it is somewhat misleading to use the most problematic vegetable (cauliflower) to illustrate that other vegetables are also problematic.
The point of the picture is to illustrate that it is possible to find insects in vegetables. Regarding your next question that there seemingly are no chances of EVER finding infestation in packaged frozen broccoli. You are most welcome to argue with the author of the sefer we are quoting, but just bear in mind that he is known as one of the world’s experts regarding infestation and halacha. Additionally, he is quoting US government standards, reports by consumers and experiments, but if you wish to argue you can. You can’t powerwash broccholi, because it will turn into mush, and soaking it might not release the grip of the bugs. Even if the bug doesn’t survive and die they are still forbidden to eat unless they get chopped up, which is questionable if this happens when broccoli is commercially washed.
As far as Kale is concerned, the author states clearly, a few lines down that the amount of infestation depends on the makeup of the individual vegetable, and the type of insect. Again the illustration is there only to give the reader the understanding that it is indeed possible to have infestation in vegetables.