Do you really think Amazon is going to let anyone sell any drugs?
Except, they are.
To begin with, selling counterfeit goods is flat out illegal.
Electronics have safety standards they are supposed to be tested against. Even clothing has safety standards around flammability.
If you dig deeply into generic drugs, they actually aren't all that well regulated[http://fortune.com/2013/01/10/are-generics-really-the-same-a...]. Legally a generic drug only has to be 80% as effective as the brand name drug it replaces, for psychoactive compounds that can be the difference between working and not working at all. Not so great for anti-depressants (or the vast majority of other compounds for that matter...)
https://en.wikipedia.org/wiki/Dream_Market
https://www.reddit.com/r/Dream_Market/comments/6pp9oi/dream_...
Are there issues when anyone can provide a product? Yes. But this would certainly not involve Amazon opening the storefront to allow selling any sort of drugs, but rather them sourcing generic product themselves and selling it as private label.
I would have no problems trusting this product to be genuine, just as I have no problems trusting their other private label products. It's a different sort of issue.
What's the story here? I purchased on (that failed quickly) and then another - which also failed - and gave up on those. I've actually never found a USB cable (that I often use as a charge) that I liked, but I've never set out on a quest to do so...
Is the AmazonBasics USB cable a well-known lemon?
Amazon is _notorious_ for having counterfeit items commingled with the same bin code (I might be using the wrong term), e.g. for cellular phone chargers, and even things like t-shirts.
Because of this, I share the GP's concern that Amazon would to a terrible, un-trustable job at preventing such commingling of pharmaceutical products. Sure, their pharmacy suppliers might make them right, but that doesn't prevent some random jerk (or just someone w/ crappy safety practices?) from posting a counterfeit with the same labeling.