Fake reviews have been an easy exploit for sellers for a long time, and sellers will often buy from competitors just to leave verified bad reviews. It's an ugly game I don't have an answer to.
Amazon recently introduced Vine: https://www.amazon.com/gp/vine/help
Amazon's shipping schedule is really bad because they hold your items hostage unless you pay for Prime. It's essentially blackmail to get your item in a reasonable time frame.
As a non-Prime subscriber it usually takes 7-10 days to get an item if you use their free shipping or 5-7 days if you use the cheapest paid shipping option.
The funny thing is, in those non-Prime free shipping cases, the item is usually processed / shipped after 7-8 days and then arrives in 2-3 days.
While it's a good program, there are millions of items, unlikely to have them all covered by Vine users. They would have to extend the program greatly for this to be an effective counter.