Why is it that the companies mining it keep their practices so deep in the shadows?
Because as you are highlighting, it's a false narrative. Just like when Eric Schmidt said "Worrying about a computer reading your email is like worrying about your about your dog seeing you naked". It's a false narrative because your dog cannot record everything it sees and play it back on command. Maybe sometimes data is like sunlight, other times it's like a searchlight coming in your bedroom window illuminating for the company wielding it, all sorts of things you would not voluntarily allow to be illuminated.
Do you suffer painful hallucination? -- Don Juan, cited by Carlos Casteneda