I think I happened to experience it using kwrite, or maybe also notepad++ when I had to edit something from a non-default computer once. The point still remains that editors which /try/ to be smart and helpfully correct, convert, or automatically indent things, won't always do it the way you might have wanted. What works in one context won't work in others, and having context sensitive whitespace handling can bite you when the program isn't aware of which context it's supposed to be crafting the document in (EG when you start a new one or copy an example from the web).
Programmers with experience will expect things to behave like the languages they know. If you are experienced with Python, Haskell, or YAML, they won't seem like surprises.
Funny that Notepad++ and Kwrite have given you problems, those are usually fairly good editors and should be able to write Python / Haskell / YAML just fine. I wonder what happened to cause those problems.
Not being able to use tabs in Haskell is annoying for example. And I find having to indent stuff so it is off the page to the right to get stuff to compile unsatisfactory.
Same with YAML. I detest a format where indenting matters. It shouldn't matter.