Hi srobinson,
I have a post on CG about it (
link):
The display of roast dates (or "Best if used by" dates) on the bags is certainly the choice of the retailer or grocer. The 'Best by' is more ambiguous for the retailer, easing their window of "Freshness". This is how most perishable products are marked - bread, cheese, etc.
As for roast dates on our bags, there is certainly Julian dating on the UPC code sticker. This is pretty easy to decipher if you know how, it's just a little more hidden.
For example,
05158 would be for today.
05 - year
158 - 158th calendar day.
Basically, groceries (or any accounts, for that matter) have the option of displaying roast dates or not. We put them on everything, but some places it's just harder to find/decode.