First-order effects

• iPhone users gain an instant price check inside any store carrying barcoded goods, moving the purchase decision from the checkout line to the phone screen.
• Amazon turns every brick-and-mortar aisle into a live entry point to its own catalog, at essentially zero marginal cost per store entered.

Second-order effects

• Physical retailers face their shelves functioning as free showrooms for Amazon inventory, forcing questions about price-matching policies and whether to resist or court in-store smartphone use.
• Rival e-commerce players are pressured to ship comparable scanning clients of their own or cede the in-store comparison moment to Amazon's app by default.

Third-order effects

• If scan-and-compare becomes a habit, ownership of the scan moment — and the catalog behind it — positions whichever company holds it between the shopper and every physical store, a structural shift toward mobile devices mediating offline retail.
• Retailers who cannot compete on transparent price lose leverage over the final purchase decision even when the customer is standing in their building, accelerating pressure toward experience- or service-based differentiation.