[AFreeBird]

What business reason do they have for keeping track of people’s locations?

In the aggregate: Usage and density patterns help determine resource allocation. Bandwidth, tower placement and densities etc.

[driftdiver]

Heaven forbid they should use call volume to manage those things.

[Little Ray]

That makes sense. Still the logs could be de-identified. No need to keep track of WHO is there, just how many, when and what traffic.
As I said, perhaps its a business opportunity.