Milord But I really have to believe that a 40+ woman isn't, in the rare case she have to, able to hide something to her mother? Something as easy as a phone?
When living in the same house and the mother doesn't believe in the daughter's right to privacy? I think it would be possible but extremely difficult.
Of course, if you are in this situation, you have either failed to establish what I would consider the bare minimum healthy boundaries for a parent/adult child relationship or you have opted into a non-standard parent/adult child relationship like Renita has. Also, my understanding is that she doesn't live with her mother, so it would probably be much easier for her to hide a device from her mother if she were so inclined than in the hypothetical we are talking about.
Regardless, we should probably get back on topic or move this discussion to the thread on parental controls, since it isn't really relevant to @Tasha