Corned Beef Brisket (and a mild rant)

I love corned beef brisket.  Unfortunately it is only available in grocery stores around St. Patrick's Day.  This is why I try to buy three of them so I can stash a couple in the freezer to cook later in the year.
This is actually a mild rant about those grocery store "loyalty" cards. I went to my usual supermarket (Publix) yesterday.  They advertised corned beef brisket priced at $4.99/lb.  They don't require a "card" to get that price.  Unfortunately, they only had one left.  I bought it and put it in the freezer.
This morning on my way to work I stopped at Food Lion to buy a couple more and fortunately they still had a few.  But Food Lion requires what they call an MVP card to get the same price as Publix ($4.99/lb.).
I paid just over $19 each for two of them at Food Lion.  Both slightly over 3.5 lbs.  If I hadn't used the Food Lion "card", it would have cost me $23 more for the two briskets.  It says so on the receipt.  My question is WHY?!
This is what I don't understand about those loyalty cards/apps.  Let's pretend I was visiting friends or family from a place that doesn't have a Food Lion [insert other grocery stores that require loyalty cards/apps to get the best price].  I'd have no reason to have their "card".  Let's further pretend I decided to go to this grocery store to buy a corned beef brisket to cook for my friends.  Is there any logical reason why I should have to pay $30 for a corned beef someone with the *card* could by for $19?  I can't think of a single reason why they are allowed to price gouge someone simply because they don't have a store loyalty card.
Jill