I'm pretty sure the post you're replying to isn't talking about an iOS app, so IOKit doesn't have anything to do with it. They're saying that a store could install their own cell antenna to listen to nearby cell phones, record unique identifiers, and track customers that way. Apple is anonymizing MAC addresses to stop a similar form of tracking, but it won't work if there are other radio signals they can't anonymize.

Apologies if you knew that and I'm just not understanding your point.

Correct me if I'm wrong, but $tracking_co would just need to get their instore-tracker5000 approved by apple and then they are back to their old ways? I know that may not be cheap/easy for them, but still reasonably within reach.

Wouldn't you also need to install their application? The previous technology used builtin features (wifi scanning).

Yes. And for that use case - intentionally tracking one's location (for maps, proximity alerts, etc.) through an app - there is iBeacon.