I've had to drive an occasional windowless van for moving stuff. And I've packed my car solid so there is no rear view. It is definitely off putting when you glance up and there's no headlights behind you but you know you are surrounded by vehicles.
But if it's legal to have moving vans with no rear window, how would you justify that it's illegal to block a rear window? You can literally take the passenger version of a full-size van, and the cargo version which has no rear windows, block off the rear windows on the passenger van and suddenly it's illegal.
I've spent an unreasonable amount of thought on the line Janet sings in Rocky Horror: "His lust is so sincere". Now, on the surface, that's a big "DUH!" because that's the nature of lust. But wait: Brad has earlier sung about how hot he is for her, and it's pretty clear he's just being conventional. Brad's lust is not sincere.
Now, I could swill green mead and gnaw raw meat with sincere lust. As for kimchee and lutefisk, well, those would be just for effect. And if I'm just going for effect, I might as well wear a tie. And pants.