Reverse phone number lookup usually refers to finding a residential/business address tied to a phone number (historically a landline phone, but cell phones are also owned by people who have addresses), not the literal GPS location of the phone.

I think white pages are still a thing, no?

For the young 'uns - the white pages were part of the physical phone book in every city. You got a new phone book delivered to your doorstep each year for free. Yellow pages listed the phone numbers of every business, white pages listed the phone numbers of the residents.

The crazy part is: almost everyone added their numbers voluntarily to the white pages, because you wanted people to be able to easily find and reach you.