Absolutely they are. Nordstrom and Home Depot got called out for doing it 8 years ago - https://www.forbes.com/sites/petercohan/2013/05/09/how-nordstrom-and-hom

Absolutely they are. Nordstrom and Home Depot got called out for doing it 8 years ago - https://www.forbes.com/sites/petercohan/2013/05/09/how-nordstrom-and-home-depot-use-wifi-to-spy-on-shoppers/?sh=13565a394362 https://www.forbes.com/sites/petercohan/2013/05/09/how-nords.... The technology has progressed significantly since then. I've worked on systems designed to send in-store customers custom, extremely time limited (< 1 hour) coupons based on where they are in the store and where they linger. Linger time being used as an indicator of purchase intent for a specific item. This does require that the customer has the store's app installed and running.