@Philip
<<If the BBC starts using my bandwidth to the extent that I start paying my ISP for bandwidth that I did not authorise to use then that is a MAJOR CRIME.>>
No, that is you not reading the instructions that come with the p2p program you are using. If you ISP charges you by the Mb, then obviously the first thing you do is check whether the programs you use to access the internet do not have settings that allow them to perform unsupervised data transfer.
P2P data distribution is perfectly legal. Whether it causes problems for you due to personal circumstances is then your own responsibility - don't use it if if will negatively impact you.
Along same line of reasoning, it is the user's responsibility not to distribute illegal data. You *can*, but that doesn't mean you should, or should get away with it. That said, there are plenty of legal P2P applications (video, large tester or plain free applications, data sharing amongst specialised communities such as university science faculties and corporate R&D centres). Blocking all forms of P2P distribution because a fairly large but by no means 100% part of the users use it for illegal data distribution is solving the right problem the wrong way, by doing something illegal yourself.
And yes, the post is a fully automated system, only requiring human help when it encounters letters and packages it cannot determine the destination for, or are odd-size and so do not fit through the automated systems. It already scans your mail for certain substances, it would be trivial to add in an extra screening for CD shaped objects with a little slot they fall through straight to the shredder. Would that work? yes. Would it be illegal? equally yes, because it would be indiscriminate (you could burn a CD with 100% legal data on it and mail it to someone, and it would get shredded just the same as the illegal DVD Mark would hypothetically send.
Welcome to the 21st century.