I think the distinction between printer and publisher is being lost here. KDP is a publisher, and a very cost-conscious one at that. You would have a very different experience with the editorial process of a different publisher, as most don't use Amazon-level automation.

I wouldn't even call them a publisher. They're a printer, drop-shipper and a book store. I am both the writer and the publisher and I hired my own editor. A lot of companies call themselves "publisher" but really aren't.

Indeed the experience with other printers has been better. Same with e-books (so far). In fact at this point I'm quite happy I didn't use Amazon.