A sharp teardown of why a retail barcode is not a price tag, but a product identifier that lets checkout, inventory, suppliers, and shelf operations coordinate through one scan.
A checkout scan looks like a price lookup, but the barcode is really carrying a product identifier. The price, inventory change, receipt line, and reorder signal come from the retail systems behind the scan.
Sources
GS1 US: What is a GTIN? - used for the GTIN definition, barcode/data-carrier distinction, and POS database price lookup behavior.