Huh? This is how it already works, cell companies themselves have this data. And they sell it.

The "strict guardrails" don't work. Never did.

You are entirely incorrect.

Here is the LLM's summary of the current legal issue at hand:

Attempting to determine the identity of an unknown individual co-located with a victim at a specific time requires a reverse-location query. Because the Supreme Court has not yet established a unified national doctrine for these searches post-Carpenter, lower courts are highly fragmented. Many magistrates systematically refuse to authorize geofence warrants or tower dumps, citing the lack of individualized probable cause for the peripheral, innocent devices swept up in the geographic net.

And indeed, in my case, the police were not able to conduct this geofenced investigation (which would have instantly idenitied the person).