Amazon like many other bigger retail think of safety of their reputation and still thinks Bitcoins is not legalize hence won't have anything to do it. But if it is adopted like other e payment like paypal, It would have receive amazon's endorsement.
The current legal status of bitcoin is the main concern and of course its volatility, its hard to use bitcoin if it continues to pump and dump maybe if Libra coin succeed they will soon use it. I also believe that someone in Amazon is investing on bitcoin, they can’t just ignore the potential of cryptocurrency do maybe they are also investing for different purpose.