The latest evolution in these are really devious: A shelf tag advertises a price in large print: $7.99 with smaller print "with digital coupon" And then underneath, in the color usually used to show the "non-sale price," you see "$12.99." A lot of people just glance at the tag which looks a lot like the normal 'sale price' tag and thinks they're paying $8. Of course, you have to get in the sluggish, stupid app, and best case scenario scan the tag or the item and get to the right part of the app to "Clip" the coupon. Assuming you can get a good enough signal in that part of the store, and that you haven't become logged out of the app... etc. etc. And assuming you don't make a mental note to clip it in a minute when you get out of this crowded aisle and then forget.
I think they just really want to display one price and charge a much higher one to most people.