How much of this racket on places like Amazon and Yelp would be killed if you had a unique generated ID assigned to you once you purchased a good or service and it was verified as delivered?
Right before Christmas this year, my dad got a package of some iWatch bands he didn't order, and some other small accessories. It was addressed to him, from some random name he didn't recognize. He asked around all of his friends and family to see if anyone ordered pseudononymously. Presumably this was done in order for someone to be able to generate a fake "verified review" at the peak of Christmas shopping.