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.
The RF system doesn't use the same protocol, it's a new protocol (to potentially hack and reverse-engineer).
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.
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.