Privacy advocates got access to Locate X, a phone tracking tool which multiple U.S. agencies have bought access to, and showed me and other journalists exactly what it was capable of. Tracking a phone from one state to another to an abortion clinic. Multiple places of worship. A school. Following a likely juror to a residence. And all of this tracking is possible without a warrant, and instead just a few clicks of a mouse.
Yes, imho, and increasingly so.
In an environment where the vast majority has one people act like everyone has one (eg restaurants having qr links to menus).
Even EU ruled as much (eg my company phone is my own personal device regardless of ownership & my privacy is protected differently than eg my work PC or laptop).
And even if this wasn’t the case, why would you need to opt out of having a mobile phone just to get basic privacy?