Auto complexity
I know I do a lot of spelling mistakes. Over the years I have learned to spell most words correctly and whenever I'm not sure I usually check the correct spelling. So most, if not all of those typos are accidental.
Sure I could (and I do, to some extend) use spell checker, autocomplete functionality or any other tools that could fix or point out those issues. But they aren't without their own problems either. They don't always offer the word I intended.