The biggest hole that I can find in your explanation is that Starbucks' rewards program is centralized whereas most crypto's are de-centralized.
This is my favorite video explaining the blockchain:
https://www.youtube.com/watch?v=bBC-nXj3Ng4&feature=youtu.beI think it does a great job of breaking it down into easy to understand information. If your friend has half an hour, I'd send him that to get a basic idea of what's going on.
Thanks a lot mate!
Ah right, I forgot about that! Would I be right in assuming that, in my analogy, if the distribution of the tokens was regulated by all users of the stores world wide opposed to the owners ot the company that would represent a decentralised company?
Going to give the video a watch on Friday when my internet is installed at my new house and I no longer have to destroy my mobile data via tethering