You can know it doesn't if it literally can't. Likewise if it can it might. I got thinking about this the other day when, in the grocery store, I was counting cameras waiting in line. They can watch you in particular the entire time you are there. They might. Or they might not be real cameras at all. They only way you could know they aren't surveilling you is if you know without a shadow of a doubt there are no cameras at all. If they can they might. If they can't they won't.

I tend to think about my personal privacy this way. Sandbox what you can. Don't have what you don't need. But at the end of the day, your phone is a computer you always carry with you, so you can never really know for sure. Mitigate what risks you can and don't worry about it past that. Life is too short.