Magic the Gathering cards come to mind! Buying MTG cards from Amazon can be a little risky as there is a non zero chance of getting a box with already opened packs [0]. Customers buy the product, take the valuable cards out, reseal it and return to Amazon. Amazon just throws it in with the rest as they doesn't know how to properly check for tampering.

[0] : https://www.reddit.com/r/magicTCG/comments/omj8jh/amazon_cus...

Because the supply chain to an arbitrary vendor may not be secure.

With electronics, it’s common for suppliers or distributors to supply bad parts, especially in times like now where parts are constrained.

I wanted to buy a Sony phone direct from Amazon. I specifically bought "Shipped and Sold by Amazon" three times and had to return it three times because they kept sending me another seller's commingled inventory. It was obvious because the box had the third party seller's sticker on it and it was a Hong Kong model phone which would not work properly in the USA.

Because I'd have recourse for getting a fake if there were traceability.