This is not the case for groceries in Massachusetts at least. If there’s a discrepancy between the tag’s price and the scanned price the store must charge the customer the lowest of the two: https://www.mass.gov/price-accuracy-information
https://www.theguardian.com/us-news/2025/dec/03/customers-pa...
That seems shocking to me, but I guess I live in a country where the prices on the shelves are "final" (with no need to add taxes) and I think it would be immediately obvious if I'd been charged the wrong price for goods.
[0] https://www.theguardian.com/us-news/2025/dec/03/customers-pa...
To me this is about having protocols that are suitable so not anybody can write to these labels without knowing a store secret or using replay attacks.
it's mostly about efficiency. IR based, an employee needs to physically walk around. RF based, place a transmitter or two in the building and the system now works fully automated.
With the same vulnerable protocol the RF system is as easy to attack with bigger consequences then it seems....
The early shelf-label systems were IR-based, sold in bulk and were programmed manually using handheld devices held against them.
Most shelf-label solutions of today are part of a service-model, where gateways are mounted in the store to wirelessly update any label on price-change, often orchestrated remotely so store-chains can update all shops simultaneously.