The discount is designed to be selective
A brand usually cannot charge every shopper a different price at the shelf. A coupon offers another route: keep the regular price for most buyers while letting price-conscious shoppers claim a lower one. Economists call this price discrimination—charging different effective prices to different customers, based on what they are willing to do to get a deal.
The effort acts as a filter. A shopper who searches, saves, and presents a coupon is more likely to be watching the budget closely. Someone who buys at the regular price may value convenience more, or may not care enough about the savings to seek them out. The coupon lets customers sort themselves into those groups without the brand having to ask what each person would pay.
Why not just lower the price?
A universal price cut would also discount purchases from shoppers who were already willing to pay full price. That can shrink revenue without bringing in many additional buyers. A coupon makes the lower price conditional, so the company can attract deal-seekers while preserving the higher shelf price for others.
The tradeoff is that some eligible shoppers never redeem the offer. That is not necessarily a flaw: the discount costs the brand only when someone uses it, and the extra steps help keep redemption from becoming universal. For shoppers, the practical result is a choice between paying more for convenience and spending time to pay less.
