film industry - Why do cable and TV have watermarks on their programming?

When I first got Cable TV I noted that most programs had an intrusive logo on the top or bottom corners that distract from the movie watching. In time I canceled my subscription as I didn't see why I should pay for programming when I can see it logo free on TV.

Then..

About 10 or so years ago, well at least in my country, TV stations started doing the same thing by adding these intrusive logos to the programming. To me its a form of vandalism and can spoil a movie. Especially when there is a dark scene and you see their logo blaring on the screen.

For paid TV I cannot understand, for TV I can sort of see a reason as we started to get DVD recorders and the resolution of the programming the TV stations were sending are at a fairly high quality, so piracy was a possibility.

But for a paid service like Foxtel (Australian Cable Provider) to charge $100 a month with this on the screen I think is loosing them business.

So the question I have, is there some rule/regulation from the content providers that say when broadcasting on TV they have to add a station logo?