Many free wifi places will track and report movements with the wifi area. Using bluetooth in addition. Shopping malls in particular can use this to find where

Many free wifi places will track and report movements with the wifi area. Using bluetooth in addition. Shopping malls in particular can use this to find where people congregate. Can probably be related to email addresses too, and hence shared with every other mall with same ownership as well as the company that provides the free wifi. e.g. Aruba, Meraki, ...