Many stores have installed Bluetooth beacon tracking that will monitor all customers cell phones (or other Bluetooth devices) precise location throughout the store.
The items on the receipt can work as a “checksum” for a specific pattern around that time of day.
Self checkouts also have cameras that can identify biometrics, repeat shoppers, and other data points for a profile. But it’s not known is the customer used one of those kiosks.






The app database and store database are separate, both containing duplicate data on the receipt or any affiliate data sharing that can facilitate de-anomyzation.
A lot of retail -even my doctor office - do use this and have for a while.
BLE customer monitoring is certainly a thing. Here is an article from 2014: https://www.retail-innovation.com/carrefour-track-customer-journey-around-store-using-ble/
Here is a more modern ad-riddled writeup. https://www.encstore.com/blog/5162-a-step-by-step-guide-to-using-ble-beacons-in-retail
There is even a data broker claiming it records and updates your advertising profile before you get to the register. I wish I bookmarked that page when I read it years ago.
Disabling Bluetooth, I suspect, would stop tracking. Note some modern phones still respond to Bluetooth and tracking when powered off, such as the Pixel, unless Bluetooth is disabled before shutdown.
Basic cameras can do that, but companies like Walmart and Home Depot have more advanced systems. Walmart profiles customers and can identify and alert staff/police to repeat problem customers. Home Depot has a class action case claiming it uses face detection technology. Heck, my cheap-ola off-the-shelf home security camera can track people and license plates straight out of the box. The Flock cameras tracking people and vehicles all over the cities use an OS released in 2017. This tech is prevalent now.