After getting doubletalk and eventual confirmation from Amazon that they are forcing their customers to use 2-factor identification to log in to their accounts -- that is, if the customers are using VPNs to access the site -- I emailed my VPN provider to see what they thought of this.
This has nothing to do with the recent hot issue of people outside the US using VPNs to watch Region 1 videos on Amazon; this is Amazon treating all VPN traffic as suspect.
I received a response from the VPN company, likely robo-generated. Might as well have the letterhead "from the desk of Jeff Bezos":
As we understand you are asking us how to use Amazons Two step verification process. [no, I wasn't --tm]
We do not have the specifics in regards to their verification method, however we are aware that most companies that are very security focused will require additional authentication when you are trying to log in while using a different IP address than what their system is used to you logging in with.
This is done to prevent un-authorized access to your account should someone obtain your log in credentials.
We are not able to circumvent their system. You will need to continue verifying your account as they prompt for it, or set up their Two Step verification feature.
VPNs supposedly offer privacy relief from The Man's intrusive tentacles. Why should anyone be forced to use the same device that Amazon is accustomed "to you logging in with"? Is a web transaction for the seller's convenience only? Does Amazon want this user consistency for "security" or as an aid to geographic-based marketing?
With all that in mind it was a bit surprising to read this enthusiastic defense of the "security policy" of probably the worst monopoly company. Even Walmart doesn't force its customers to use 2-factor, just to order a tube of toothpaste (yet). This particular VPN company promotes itself as techno-libertarian -- kind of a joke.