Apparently Amazon’s own print on demand service produces high quality books but it is impossible to know what sort of book you are getting until it arrives.
I ordered an audio CD set from Amazon.jp and it arrived faster than it would by US ground and the packaging was flawless, with Apple-esque plastic attached to the easy-open cardboard to keep every corner perfectly sharp.
So... it varies by region?
Or I’ve gotten lucky, n=1 ;-)
(Aside: that’s the annoying part about Amazon, 9 times out of 10 it’s exactly what you expected but then there’s that one time, maybe you buy something you wouldn’t normally, or the box is mostly empty, or the item’s serial number is invalid, and... you really don’t know what you’re going to get sometimes. And Amazon doesn’t make it easy to report it, it’s simply not something they visibly care about...)
In Europe a number of companies (most notably shoe company Birkenstock) are refusing to sell on amazon due to them mixing fake and real products and the producer gets the losses AND takes the commercial and reputational hit when things go wrong.
In the late noughties/early onesies I went through this period where I realised I could just buy anything I wanted that wasn't food from Amazon, and it was briefly great. However, they have had a huge problem with counterfeit, poor quality, seconds, and reconditioned goods for a number of years now. If you need thing X you're much better buying it from a specialist retailer, direct from the manufacturer or - depending on what it is - even from eBay, Gumtree (or its US equivalent Craigslist), particularly for used items.
Avoid Amazon like the plague for non-media items.