Not to mention that if you have any app with admin rights, it can be triggered remotely to switch on any aspect of your cell phone.

There's a level of trust required to use anything you didn't build or can't audit. If someone needs to surveil you, and in the US a judge has agreed, someone can probably make it happen. That said, in reality most of us will never be under scrutiny simply because there are so many of us. It has to be automated. It's too vast a pool of people. By the time someone real is twigged that you are a good candidate for surveillance, you are probably already aware that you need to hide. It is very hard to hide in our modern world, though. Off the grid entirely.