I came to a good analogy - Imagine sending that card number using HTTP form to a HTML target URL. You wouldn't return 4xx code if a card is not found. The user

I came to a good analogy - Imagine sending that card number using HTTP form to a HTML target URL. You wouldn't return 4xx code if a card is not found. The user would see your 404 page or browser 404 page and think the page doesn't exist! API shouldn't be different.