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.
Search and seizure, the Fourth Amendment, only applies to State actors. The only exception is when a private entity is acting as an agent of the government, such as in the case of private prisons.
Congress needs to pass consumer protection laws aimed at privacy in the digital age. They haven’t updated this sort of thing I believe since 1996. It used to be legal for adult video stores to disclose the tapes people rented, but Congress passed a privacy law forbidding it when some journalists disclosed some of their rentals. The scandal had some cool name. I forgot what.