Amazon casts shade at retail rivals with its first public Prime Air delivery - a box of sunscreen

Amazon is reporting the success of its drone delivery service, having announced the completion of its first public US drop-off.
The Prime Air project was showcased during an event at the Mars Conference in California  which annually displays 'Machine learning, home Automation, Robotics and Space exploration' innovations to invited guests. 
During the exhibition this week, Amazon had a fully automated flying drone deliver a package filled with sunscreen.
It has been a long-time com