It's far from unique to amazon, though. The Microsoft employee/contractor decision in the 90s made it socially acceptable to treat contractors like shit, and it's been downhill since then.
I also imagine its a complex and fun problem to try and solve. Ive noticed they have started in some ways, for example some brands are now labeled as "premium brand sourced" which means less likely to be fake.
Previously (B2C): incentivized to deliver great customer experience to make money on increased sales volume and higher-price purchases
Now (B2B): incentivized to deliver easy seller experience to make money on increasing number of sellers and sales volume
To be fair, Amazon still cares a surprisingly amount about its end customers, when it doesn't need to, as a legacy of its rabidly awesome B2C days...
... but over time the company will continue to errode and optimize itself to its current customers (sellers).
Why doesn't Amazon do more to strategically combat fakes / bad products? Because sellers literally don't care about that. It's not a priority for them, so it's not a priority for Amazon.
Amazon is now for the “we technically have QA but honestly don’t give a shit” sellers. Not quite alibaba but getting there.
The core distinction between Ebay and Amazon is that on Ebay each shop+product combination is its own listing and the seller reputation is put up front, with the buy button below the seller information. Meanwhile on Amazon there are product listings, with multiple sellers providing the same product and the seller name being put below the buy button. There is no obvious indication that you are buying from a third party seller on Amazon, whereas on Ebay you can only buy from third parties, so expectations adjust accordingly.
Makes for using independent store fronts a breeze because almost every checkout experience through shopify shares a common login and CC info.
Prime (no pun intended) example of enshittification [1].
[1] https://www.wired.com/story/tiktok-platforms-cory-doctorow/
[1] Only Amazon Resale third party resellers are shown https://www.amazon.com/Amazon-Basics-Anodized-Non-stick-Stac...
EDIT: This is not a secret, but by all means, keep downvoting me.
If you are in the USA report unsafe products here: https://www.saferproducts.gov/