I assume everyone who uses mobile networks has their location data being stored, shared, and sold by the mobile network companies. I assume government agencies and other people in positions of power can easily get identifiable information, and advertisers or other businesses can purchase "anonymized" information. At this point, I'm not sure what else is left to protect.

https://arstechnica.com/tech-policy/2018/06/verizon-and-att-...

They claim they're stopping, but I don't see why I should believe them.

Because one industry does it, does that mean we just give up and let everyone do it?

Mobile network location data is much more coarse than GPS data, so there's "that" to protect.

Are you sure? If the data in question also covers WiFi signals, which include the signals emitted by every phone near you, then I'm not sure the data really is that coarse.

I'm presuming here the location data is gathered outside of the phone (eg. by cell towers), not the phone itself. If you have access to the phone itself (eg. malicious app), then you can easily get GPS data as well.