I just checked my Amazon orders. For the last several years I've been ordering between 100 and 150 items a year. Before 2008 it was closer to 40 or 50 a year. Before 2006, when I got Prime, it was 6 or 8 a year.
Those items are predominantly small purchases but quite a few were laptops, desktops, monitors and tablets. I have a lot of computer stuff.
I don't have any record of my returns but just offhand I'd estimate it was less than 5 a year. Probably half that but I'm not very sure of that.
I once bought an Archos tablet, several years ago, that was defective but the price had dropped so much I ordered a replacement. Six replacements later I finally got a good one. That year was probably when I had the most returns.
I also ordered one of the early Acer Windows tablets for about $700 and kept it for a couple of weeks and decided I didn't like it and returned it even though there wasn't anything wrong with it. Amazon never expressed any qualms about that. That might be the only thing I've returned simply because I didn't care for it.
A couple of years ago I had problems with something, I forget just what, and I got their support people on the phone and they were helping me figure out what to do about it. I didn't know what to do or what I wanted to do or what I could do and I told her that and she said something like "With your customer status you can do anything you like and it'll be fine." I didn't ask her for more information about that but it really surprised me.
At least that does tell me that they have some way of rating their customers. I have no idea what it might be. My guess is it's based on my amazing good looks.
Barry