[Jack Black]

Any local cop seeing that van on the street would have pulled the driver over and cited him for obstructed visibility. The owner would have been forced to remove most of the stickers

I don't think so. Tradesman vans most commonly don't have side windows.

Some of them also don't have windows on the rear doors, for security of tools and other items stored in the truck overnight.

[Windflier]

Tradesman vans most commonly don't have side windows.

Most do, but I've seen models without rear side windows, and models without rear door windows, but I've never seen one without either.

I own two of these, myself.

I'd have to research to see if they're made without any rear windows at all.