why the hell aren't store loyalty cards and coupons connected?

So, I was just talking about this with my wife and if this exists, I need someone to put me on.

So, if you have a store card, let's say Publix, and it's tied to your phone number. You put it in, you get whatever discounts and it comes off your total, right? Why can't you put in the coupons or coupon codes into thier store website and have it so those coupons could be compared to what you just purchased and be deducted the same way?

To go even further, if you do scan and go, like at Sam's, it will tell you "there's a coupon if you buy 3" or you could get this much off if you got this brand/size/quantity instead.

Does something like this exist? even as a 3rd party?