I know somebody else who failed it because they had newspapers strewn across the backseat!!!
Ah but you see with the window open, a breeze could have caused a big double spread to flap and flutter around the interior like a paper pterodactyl and the spine could just settle on the bridge of driver's nose like a big tent - then of course there would be lots of flapping around yelling and panicking (but no attempt made to actually remove the paper) and before you know it the front bumper would be hugging both sides of a tree trunk - and one wheel would be invariably slowly rolling down the road (but thankfully no-one would be injured).
At least that's what happens on tv anyway.