They're not good practice on the part of the website operators, for sure, but they are real examples of the root and www domains being different. In my experience there are also lots of old or government sites that just plain don't work without the www.

And when the person phones up tech support “ma'am, does it show the www. in front of the website?” “no” “sorry you need to retype” “it still doesn't show www.” is going to happen.

Or someone will write down the URL from the screen, and when someone else types it in, it won't work.

Oh, right, and there's the same issue with sites where https:// has a different site to http://!