Spot on at least insofar as copying for personal back-up reasons is concerned.
However, the fact that a law generally isn't enforced isn't a defence if the authorities do decide to prosecute (though, of course, it will reduce any penalty).
As for why we permit dvd copying discussion here, well it's perfectly legal for back-up purposes in many countries in including Holland (and Dutch law is the law that applies to this forum since that's where the forum and its servers are based.)
What's legal and what isn't varies from country to country. For example, it's perfectly legal to make a back-up copy of a movie Dvd that you own in the US. However, you're not allowed to bypass or strip any digital encryption to do so (which, of course, makes using AnyDVD, Dvd Decrypter or any other CSS stripper illegal in the US).
The effect of that is that the fair use "right" to make a back-up copy of a movie Dvd that exists in the US is essentially useless. In effect, it's only use is for unprotected dvds and there aren't too many of those about.