Why would anybody use cash back when transactions fees have to be paid .....are you suggesting bitcoin services should be free 
Honestly this sounds a phishing attempt!
Honestly this sounds a phishing attempt!
The transaction fee may become insignificant in the future to be worried about.
I kind of like op idea. Stuff like that are better developed as side chain or dApp than on main chain.
Blockchain core ideals should remain unchanged. Every other deviations should be built as sidechain or dApp