Privacy in the age of implied consent

I'm quite amused by cries about FB's onslagutht on privacy (all in all, you *did* give your consent, didn't you?) while more interesting things are happening.

...so I bought a new phone. Been methodically transferring working pieces from the old one, and found myself driving with the old phone connected to BT monitoring hardware in the car with the new one running navigation.

...and in the middle of the trip the old phone (now without a SIM card) says: "Psst! Dude! It looks like you configured tethering on your new phone, why don't you turn it on and give me some Internet?"

Wait.
What?

Quick introspection shows that in order do to that

• both phones need to have a list of my devices' MAC addresses
• sniff the air to detect their presence (turns out this is pretty easy to do)
• most importantly, *know* that I have a hotspot configured.

Now, first two things are annoying, but widespread, there's not much you can do about that. But the third... I do have a hotspot configured, but I never ever turned it on. Moreover, I don't think I *ever* gave any explicit or implicit content about sending the information about my hotspot details to Google.

Your privacy is dead. Deal with it.