My problem is that what I input (and observe!) doesn't match what's persisted. Worse still, editors lie about it to me until I close the file and reopen it. And just to really turn the knife, various programs will then throw a fit that a character that I did not input and my editor lies about not being present, is present. I hope it's appreciable why I find this frustrating.
I expect my editor to do what I say, not secretly(!) guess what I might have wanted, or will potentially want sometime in the future. Having to insert a newline while concatenating files is a chore, but a predictable annoyance. Having to hunt for mystery bytes, maybe less so.