They save the file when they finish typing. But think of what would have happened if suddenly your computer crashed before you could save the document? You will lose all your hard work in a matter of seconds. It is a tedious task to re-do what was once done and I doubt anyone likes to repeat the work they have already completed.
I know you will say … ‘but there is a “recovery option”’. Nevertheless if you did not save the file, the first time you created it, it is not as simple to recover the file. Every time you open a new document save it first. Then if your program crashes it is easy to recover the file. Always, always remember save the file first.