Must say I havn't really noticed it but I suppose it depends on what you are buying. I don't buy clothes on Amazon at all. I do buy stationery, books, electronics etc., and seldom have a problem. I do, though, always filter by "Prime" so that I presume gets rid of a lot of amateur/dodgy sellers who won't use the "fulfilled by Amazon" system, and of course gives quick and free delivery.
The few times I've bought something that didn't work, damaged or poor quality, I've just sent back for a refund, no drama, money back in bank account within a few days, or even same day, depending on method of return.
My last few purchases are a reconditioned laptop, cheap inkjet cartridges, rexel staples, a fax roll (!), bluetooth dongle, 6 way switched extension lead, landline telephone with earphone jack, and a reconditioned iphone 12. Happy with all of them. All via Prime. Well, tell a lie, there was a very slight problem with the laptop in that one of the keys was sticky, but seller promptly posted me a new keyboard and emailed a link to a video showing how to swap it. Happy days. I'd have struggled to find any of that in our depressing High Street (laughably called as it's nothing but money laundering shops) nor the out of town supermarkets.