The more crucial difference is that the products were sold by third party sellers. I'm assuming counterfeit goods are almost never a problem if the seller is Amazon.
Sometimes you can get a solution to a problem by saying saying that after spending a bunch of time attempting to solve it, you've decided that a solution is impossible. The desire to prove you wrong is too much for some to withstand, and they go out of their way to provide you with a solution. (A consequence of http://xkcd.com/386/ "someone is wrong on the internet".)