If I as a buyer can’t tell the difference between fresh and expired food before I buy it, then what’s the store’s incentive to not sell me something a few days or weeks after its sell-by date? Even if they want to, they can’t keep track of every product on the shelves (I’ve encountered items past their date on shelves a number of times, sometimes significantly so) and they certainly don’t check each item’s date at checkout. If customers can’t do the check as they shop, there’s no way to protect against it. And just kick the shop, customers can’t open the packaging before they buy.

I do realise based on your comment and others that I may have been wrong (probably country dependent), printed dates might be intended more for stock keepers than for consumers, but that doesn’t mean it’s okay to hide this information from buyers.