Think about how this information could be used. As a store owner you can precisely track movement of customers and optimize the shop layout.

BT hardware is also rather affordable.

You're already tracked like that. I was building solutions to do it well over a decade ago. One customer was well known for their mouse themed hats. A famous hotel brand in a well known casino city used it to track employees instead. I no longer do that for obvious ethical reasons.

There may be a rare few legitimate uses for improving the accuracy, but it also makes those privacy nightmares worse.

My previous employer already had a product offering that could do this for a better part of a decade by triangulating with WiFi/BLE and cross referencing with surveillance footage. It was deployed in malls and retail chains.

It generated interesting information, but not interesting enough to be profitable.

We weren't the only ones with this capability either, most major retailers had this level of analytics through surveillance footage that previously existed for loss prevention purposes. Then simply link the data to a rewards number or credit card and you got a stable tracking identity.

And guess what, that shop layout is not going to be optimized for the customer's convenience, but for the shop's profits. These kind of solutions tend to converge on the 'Hotel California' model: you can enter, but you can no longer leave.