Apps on your smartphone only get access to your messages if you give them permission.
Now, you could of course argue that they only have themselves to blame.
I'd prefer all this stuff came with physical switches so it can be enabled/disabled in a hack-proof manner.
What's your threat model? https://ssd.eff.org/en/module/introduction-threat-modeling
For most people mass surveillance is a more realistic threat than the NSA hacking their camera.
I don't have any illusions about being able to stay private from the eyes of nation state level adversaries but commercial entities can still be kept out if you try.
While not as precise, you can definitively leak your location by scanning for the surrounding cell towers, especially in a city, which usually have hundreds or thousands of them (Manhattan alone has eleven, for example). I used to run a Python script on my Nokia phone that logged the tower ID, and I could reliable tell when I got to work, home, etc.
And that's just for people who control your phone. Your operator has U-TDOA¹, which is typically accurate to 50m.
The camera part is true, but tape is cheap :)
It's also not accurate to within enough resolution start targeting advertising and other nuisance information at me even if there was a way to present me that (which there isn't).
I'm well aware of the power of triangulation, I used to go fox hunting.
Though European laws are still mostly sane in that regard.
That's really quite a way from "hundreds or thousands".