Incorporating Loyalty cards facilitates a feeling of belonging for customers.  

Part of the Brand's Voice is a sense of belonging.  Using the packaging to facilitate familiarity and friendliness through clever copy connects the brand to their loyal customers and friends.

Bob's Shanghai 66 is an Authentic Chinese Food restaurant located in Potomac Maryland. (https://www.bobsshanghai66.com/) I love eating at Bob's but it doesn't have a clear brand voice, this re-branding of the packaging is more expressive of their target audience, and can easily be built upon and incorporated into all aspects of the brand's Design.