Similar experiences here. I'm no fan of Amazon, particularly with how they treat their workers. That said, some of their competition just doesn't offer the same range of products at a reasonable enough quality[1] making me suspect that a significant number of their items get returned or tossed.
In recent memory, I've had only one bad experience with a 3rd party seller not shipping the item I ordered. Oddly, I ordered twice before from them (through Amazon) and never had an issue. Something changed in the months leading up to the third purchase, because their reviews went from overwhelmingly positive to overwhelmingly negative, and I'm not sure COVID-19 would completely explain it (or maybe it does?). Two months after not receiving the purchase, I sent a dispute to Amazon and they refunded it in full. Can't complain.
I did have a product arrive damaged (actually a pack of two; one was fine). Amazon refunded the entire purchase price for both saying they couldn't do partial refunds (understandable).
Of the couple of other mistakes I can think of, they'd once sent the wrong item (a consumable) and also refunded without fuss, suggesting I should just dispose of the mistaken item as I saw fit. The other one was a carafe for frothing milk for cappuccinos that didn't arrive at all. IIRC, they refunded and sent a replacement the same day I emailed. Also had a hard drive show up with surface defects (placed in an unnecessarily large box and almost certainly got beat up during shipping), and I got a return label that same day with UPS showing up about a day later to pick it up. (Bonus: I know the usual UPS driver, so it was good to see him!)
Never have bought many clothing items from Amazon recently except for neck ties. Watching some YT channels that purchase from Amazon-related liquidators[2], the negative experiences with clothing and personal hygiene don't really surprise me. Worth watching, but be prepared to be somewhat terrified and maybe a little grossed out.
[1] I once bought a laptop cooling tray from Walmart out of curiosity. The quality was roughly what you'd expect. The USB cable failed after about a month of use (poorly terminated no doubt) and the tray is of the lowest quality manufacture you can imagine. Ironically, it was more expensive than better quality options off Amazon...
[2] https://www.youtube.com/channel/UC8Xi9F_8Sr1-1bKRDlCO1ZA