unseen maybe, unknown no
"we never see the data collected by our supermarket loyalty cards, our credit cards, our public transport passes, our access passes, the location data constantly being transmitted by our mobiles to our carriers, on and on, world without end."
Presumably the data on my public transport pass says that I stepped onto the S1 bus at 7:35 this morning. Perhaps collating the location data for the bus would say at what stop I did so. But guess what, I know where I got on the bus, and off the bus, though I dare say the transit authority will remember a lot longer than I shall. The carrier could track me on my lunch hour walk, but probably I have a much clearer picture of it.
If you mean that most of us do not often reflect on the amount of data we generate, true enough. If you mean that Faceborg knows better than I do that I like beer and pizza, I have to disagree.
Let me add that my preferred way to purchase books (apart from beer and food, almost the only product I like to purchase) is with cash, both to sustain local bookstores and to let the industry do its own damn market research.