You might need to talk to more ordinary people. Most people are very surprised at what data of theirs is stored, even for blindingly obvious features -- e.g. the list of everyone you've ever blocked on Facebook, which, obviously, is a list FB must store at some point in order to enforce it. Find an ordinary person and ask them to download their data from FB and Google and see if they aren't surprised.
Being surprised about things you've forgotten you did on a service, and reading a product's own marketing (and core functionality) aren't really comparable.
I just asked a non-tech person behind me if they thought that when you asked Google Assistant a question it was sent to Google to answer, and they shrugged and said yes like it was a stupid question.
What ordinary person doesn't understand that when you asked Google a question that Google knows the question you asked? It doesn't make sense.
I think ordinary people have a vague sense of how computer memory and computation works. Because online queries happen near-instantaneously (relatively speaking), people don’t assume there’s a need for this data to ever be stored, or be accessed by anything else besides the “Google” program at the point in time of the query.
Your point was that "ordinary people" don't grasp the concept that it is Google, or Amazon, or Apple that is providing the answers when they use a Voice Assistant. In spite of their entire marketing saying exactly that.
They don't need to understand "computer memory or how computation works" to grasp that the person/entity you ask a question to, has to know that question in order to provide an answer. In fact you could have never used a computer and grasp that concept.
You're trying to make this more complex to mask the fact it is a logically flawed premise.
"Being sent to Google" is absolutely the wrong way to phrase this question. Of course people understand that the device with the word Google written on it sends information to Google. That has nothing to do with the current story.
Better questions:
"Do you understand that when you ask Google Assistant a question, a human might listen to it and not just an AI?"
"Do you understand that the human might not be a direct employee sitting in a Google office -- that they might work for 3rd-pary company that Google just contracts out to?"
