This is already the case. Virtually every single food product comes with an expiration date label - which includes some kind tracking. You pretty much need to have that to do any kind of sensible recall when there's yet another poop lettuce outbreak. Looking at my pantry it usually seems to be include kind of lot number, time of production, and/or production line identifier.

I reckon they already have a pretty reasonable idea of which store it ends up going to, and with just-in-time resupply a pretty reasonable bound of when it will end up having been sold. Look at the overlap of a few dozen products and it should be quite easy to reduce the number of people who could've bought all of them to just you.

The QR codes just make this more explicit, and slightly easier to track. You're not wrong, but at least this time we could get, say, automated warnings in the Walmart app of a recall on something you bought out of it.