I presume you're talking about America, since I can assure you that in Asia QR codes are alive and well. In China in particular everything is done with QR.
I'm talking about Australia here but I imagine its the same in both countries. QR codes used to be on every poster but now the only place I see them is on the front of the apple store so you don't have to walk in (which is a process right now)
I think what killed them here is that android didn't bundle a qr code scanner by default and they never contained anything that the user actually wanted, they were just for marketers to get people on their site.