Thoughts on The Piracy Logic Problem

I just though of something that I can't get to make sense...

DISCLAIMER: I am in no way a lawyer, just a confused consumer.

It is (in Denmark at least, and I assume in most other countries) legal to make a safety copy of a legally purchased movie or album for yourself. I presume it is also legal to get a friend to make the copy for you, provided he/she doesn't make one for himself/herself as well (quite likely to happen given the time and computing power it takes to make a digital copy / transcoding) But, it is not legal for me to download a "safety copy" of a movie or album I have legally purchased.

How exactly is that different from getting a friend to make the copy, and how is it supposed to be proven that it was actually downloaded? And what about if I make backups of all my movies and albums on my home computer and my physical collection then get stolen or my house burns? Will it be assumed that everything was downloaded illegally and if not, am I even entitled to keep my backups - and if not, why allow me to make backups in the first place?

Furthermore, even if it is proven that my collection was downloaded off the internet, how can it be proven that the copy I downloaded was not ripped from my own original (in the case that your backup-friend lives far away and sending the file is quicker than getting it physically - and, for the sake of argument, that your physical collection is nearer to your friend)?

Also, in the case of someone downloading something off BitTorrent, Rapidshare or another service - how can it be proven that the "leaked" copy didn't originate from, but wasn't spread by, the person downloading it? Isn't that still a personal backup, even though others "stole" copies of it?

I'm having a great deal of trouble seeing how it's possible to separate legal from non-legal copies (except for the case of watermarks, but even then you have the possible person-to-person sale to deal with) and how you can prove that any downloading/ripping/transcoding is illegal, provided that backups are legal - and I strongly believe they should keep being legal! I don't want to lose my copy of Ghostbusters to scratches on the disc :(.

What are your thoughts on the subject?