it literally says it uses global search index on the label below the check mark. It seems more than likely that (now or at least in the long run) they will use user data to enhance this index.
It's funny how one can use "literally" while almost demonstrating illiteracy.
It's right there in the help text:
> Allow this device to privately match places in your photos with a global index maintained by Apple so you can search by almost any landmark or point of interest.
They are saying that they match your photo against their global index.
They are not saying that they will add your photo to their global index.
