Physics is still physics even in your Star Trek fantasy land. That's to say nothing of the regulatory and liability hurdes. However, the main problem with these flights of fancy is the extra energy expenditure involved. It is perhaps the least energy efficient method of transport you could possibly come up with.
What do the people that actually move things around have to say about this? Amazon is just a clueless customer of someone else's delivery service.
Finally, the DVD mailer still remains the best product of the company that killed blockbuster. It avoids many of the problems that people IGNORE when considering ALL of the issues involved in video streaming.
Even bandwidth isn't free and streaming licenses certainly aren't.