I wouldn't guess that memory is the issue so much as less exposure to this type of information in the first place. We no longer aimlessly browse stores checking everything out; now we just search for specific items, buy them, and move on.
I can probably recall the prices of things I've actually purchased about as well as past generations, but anything beyond that is basically a wild guess.
As someone who's been keto for just about my entire adult life, the humor of "I mean it's one banana Michael. What could it cost, $10?"[1] was almost lost on me.