That’s an interesting comparison! I admit it I took business law a long time ago, but I think the answer is: it depends. You’d also need to dig deep into the TOS for both the consumer side and the seller side. But ignoring the specific details, here’s my general thought process:
- products sold directly by Amazon: you have products sourced through (nominally) a legitimate supply chain, where there are legal agreements for Amazon to be a distributor of the products. If the product is faulty, Amazon is likely protected by those agreements and the liability will likely ripple back to the OEM. But, Amazon sold the product to you, and depending on consumer protection laws in your jurisdiction, may ultimately be responsible if, say, the manufacturer goes out of business.
- Fulfilled by Amazon: this gets trickier. In this case, it’s relatively clear that you’re not purchasing the product from Amazon, but rather from a company that has stored their product in Amazon’s warehouse. It seems to me that Amazon is less likely to be on the hook for this.
- Third-party sellers: Amazon is mostly just a catalogue and payment processor in this situation, not to different than Etsy. Most likely the seller is on the hook here and not Amazon. Depending on how the seller came to acquire the product (legit supply chain or other), the manufacturer may or may not be on the hook via the distribution-agreement ripple. (For example, an independent company that refurbs broken phones and resells them on Amazon is unlikely to create liability for Samsung)
In the delivery case, we’ve got an unlicensed (health inspector-wise) company distributing prepared food from a vendor they have no formal agreement with. If someone were to get sick, it seems pretty reasonable for the restaurant to shrug and say “we followed proper food handling protocols, maybe the liability should go onto the unlicensed company that bought our food, did who knows what with it, and resold it without our permission”.