My whole point in posting originally was to bring up the fact that the interesting discussion of different thresholds and having a spectrum of options is being lost in binary "privacy vs complete corporate control". It's not binary, and it does everyone a disservice to act like it can be for everyone.
Your phone's microphone can be turned on remotely and listen to what you say (I know several startups that do this). Security/traffic/drone/satellite cameras are everywhere. You are being watched literally all the time, but to think the watchers actually care about your personal life indicates a pretty inflated view of self-importance. We're starting to complain about it about 20 years too late.
If i'm on gmail, then you need to talk to gmail to talk to me. It's a tradeoff you'll need to make. If you want you can GPG encrypt the email, but there is nothing from stopping me (legally, morally, or otherwise) from just decrypting it and replying with the contents, or saving the decrypted message in my google drive.
So, by the same token, does Google have the rights to profile people even if they haven't consented to that? One answer, as with copyright, is to see what the law says; and it's very possible that the law says no, especially in the EU. (I've not researched it; others will doubtless know much more than I do.)
Or Google could just seek to do the right thing and not profile people unless they've opted in. But my definition of the right thing may well be different to theirs.
1. finding someone who is not using any Google service at all, and
2. finding their data in a Google database.