What kind of muppetry is this

Driving conditions varied considerably over the weekend, but not so wildly as the responses to the driving conditions. Some took every chance they could; others went at the speed of a funeral procession; and one very special driver wambled along the M50, not having bothered to brush off the four inches of snow that blanketed the back window.

Now, maybe there was a perfectly logical explanation. Perhaps they were ferrying the snow for some 'Make a Wish' foundation gig; maybe the snow was protecting a photo-sensitive passenger - I want to believe that's true. Because the alternative...