Still doesn't matter. For FBA stuff, they mix items in their warehouses. So even if you buy from Amazon, you can receive an item out of the FBA program. Thus you have no idea if it's the real deal or a knockoff sent from who-knows.

edit: That wasn't clear. Try two: Inventory submitted by FBA vendors is commingled with Amazon inventory in Amazon's warehouses. When you, a sucker, buys it, you have zero control over whether the widget you get was purchased by Amazon from the manufacturer or sent to Amazon by Billy Bob's Sellin' Totally Not Fake Shit Shack, which definitely got it from the manufacturer, not the bottom price on Alibaba. This is true even if you buy from Amazon and not an FBA vendor.