Drawing a blank

The IPKat's friend Richard Pringle (Shell) asks a non-work-related question, which has lots of ramifications:
"Could you please tell me, or point me in the direction where I might find out, why trade marks (and other IP) are often blanked out or avoided in other ways in films, TV shows, advertisements, etc?
E.g. the Apple logo is often blanked out on its laptops in advertisements for car insurance and many other things. The same occurs in a house-buying TV show when the participants sit at home and “watch it on the laptop”. I assume the design of the laptop (which is visible and recognisable) is a registered design, even if it’s not a registered TM; but with that level of recognition it could be registered as a TM. In car insurance advertisements, I’ve seen representations of cars with their badges removed; I’ve also seen invented representations of cars that look like a hybrid of a variety of identifiable models from different manufactures, the end result being arguably damaging to allure of the component cars. In a film I recently saw (Fish Tank), the producers had gone to the trouble of using made-up alcohol branding for all the cans and bottles in the film (scenes of alcohol abuse were portrayed in this film, but only as small element of the whole film).

What about exhaustion of rights or any of the other reasons why this type of use (if it went ahead) could be said not to be infringing use, or any of the defences to infringement?"
The IPKat is no admirer of the restrictions placed on product placement which, even though they have been lifted somewhat in Europe, still seem misplaced and arbitrary. Viewers in the United States have been exposed to the phenomenon for decades with no apparent ill-effects, and since commercial advertisements are part of our everyday life it has always seemed to him to be pointless and misconceived to blank them out of TV productions. Merpel agrees and adds: if for the sake of reality they don't blank out swear-words or nudity, it seems silly to blot out Apple logos, doesn't it? Tufty says, I'd like to do some reverse product-placement, like threatening to dress a really obnoxious character in a popular brand unless the brand owner pays me to blank it out!

The Truman Show here
How to draw a blank here
Check out the brands that aren't blocked out on BrandChannel's Brand Cameo