I think the better analogy would be the postal service using return addresses to populate a database.

Doesn't the postal service already scan every piece of mail and put those images in a database?

>> Should a sender of a letter have the right to say that the recipient can't put their address into their rolodex?

How is a global surveillance network and database like a Rolodex?

Google, facebook, etc are pretty horrible surveillance networks if that is what they are, considering you can just choose to not communicate with their services and they aren't surveilling you any more.

That's pretty disingenuous though, given that FB and Google both track you across the net whether you have an account with them or not. Logging out of your account doesn't stop them or increase the difficulty of them tracking you, or associating that trail with you.

How does facebook and google track me if I, say, install ublock or adblock?

That's actively taking steps to block their tracking rather than just not using their service. And while technically, you can use uBlock Origin to block everything from Google, that would result in many webpages being broken.

You're also likely to be using Google's DNS (8.8.8.8) without knowing, because some piece of software decided to hardcode that DNS server.

And your friends have almost certainly already uploaded your data to Google's Android backup service and to WhatsApp's database.