> Amazon has no third party seller rating ... People cannot review sellers
Sellers have reviews and ratings just like products. You can leave public feedback and a star rating for sellers you've purchased from [1]. On the 'Your Orders' page click on 'Leave Seller Feedback'. This page also describes how to do it [2].
You can see these ratings while selecting which seller's offer to buy from. For example, many 3Ps are selling '5 Hour Energy Shot Berry - 24 count' [3]. Alongside each seller's offer, you can see their star rating and positive feedback percentage. For the first seller I see a 5-star rating and "96% positive over the past 12 months (1,122 total ratings)". You can click on that to see individual feedback.
It's my understanding that these ratings influence whether a seller's offer will be chosen for the 'Buy Box', which is the default offer that's shown on the product detail page. When an offer appears in the BuyBox, underneath it will say something like: "Sold by 7-Eleven, Inc and Fulfilled by Amazon". The seller name is a hyperlink to the seller's profile page where you can see their ratings and reviews [4].
Amazon also has a slightly different problem than Ebay, as I understand it, because Amazon is trying to have a single product detail page for each "product". There should be in theory exactly one page for "24-pack of 5 Hour Energy Berry". I'm not experienced with Ebay, but it looks like every Ebay listing is completely separate and independent. Doesn't that make it harder to comparison-shop for the best offer for a specific product among multiple sellers? Is there an easy way to see all offers for one specific product? I couldn't see an easy way to do this while experimenting with Ebay search right now. Amazon is trying to make this comparison shopping easy by consolidating all offers for the same product into one page, and then selecting a recommended offer based on various factors (including seller rating, shipping speed/reliability, etc.) that matter to customers.
(However, because there is a single page for each product, and sellers have some ability to create and modify pages, that occasionally leads to abuse, like the kind being discussed elsewhere in this thread.)
[1] https://www.amazon.com/feedback [2] https://www.amazon.com/gp/help/customer/display.html?nodeId=... [3] https://www.amazon.com/gp/offer-listing/B0021L9XK4 [4] https://www.amazon.com/sp?_encoding=UTF8&asin=&isAmazonFulfi...