The apps themselves will give you the IP addresses, it's not hidden. Plus I'm sure ISPs could easily see who is using binary groups on usenet for instance.
Actually in every single instance where such action was tried, in Europe or US, the effects were less than satisfying and in some cases the public outlook was downright condemning - I'm sure most of us will remember EMI, Warner, Universal and Sony BMG starting their John Doe "caught by IP while torrenting" trial run, then taking some warez kido, 14 year old Brittany Chan into the court for sharing 829 files on her computer and then getting severly biten by press, spit bombed on TV and consequently lost in court, in quite spectacular fashion.
Drink or Die (software crackers) court case costed British side of operations over 20 million pounds, for just 6 people to be proven guilty of "conspiracy to defraud".
There is no satisfaction to be had from treating and chasing piracy as cyber crime, as it usually doesn't involve sales for profit or any definite, easily provable damage.
Why exactly any ISP needs to give their customers access to alt.binaries.games for instance is completely beyond me since the group (and many others like it) has no use apart from distribution of pirated games.
You ban warez and "pr0n" from internet and you might as well shut down the operations and let the last lost AOL user in world wide web switch off the lights. It would defeat the purpose. It would be like banning smoking and drinking in pubs. Hmmm... Having said that I can see now, how it would fit in British way of thinking....
Seriously though - it's just a buck - while lowering prices in ADSL wars ISPs were actively trying to regain control over their own market - currently almost every single ISP has "warez tax", in one way or another. It started with slow players, like plus.net, who oversold their network capacity and instead of buying extra lines employed elacoyas to actively throttle certain activities and introduce changes to usage policy, specifically so they could then offer "high volume" users special price plans. Today it is standard for most of the ISPs - they have that non profitable, heavy oversold, massively contended broadband for email and web users @ £6.99 and if you want your torrent ports unblocked and bandwidth limits lifted you have to pay extra. Whether it's the top buck "unlimited*" (*=subject to Fair Usage Policy not specified by anyone at any point until we establish what's convenient for ourselves and at what price) or paid per gigabyte of data deal, downloading loads and often is now packed into "special unlimited unlimited" plan - sold to you at extra profit to your ISP.
Interestingly enough, some of the ISPs, the more retarded ones, like Tiscali, which since rapid expansion and multiple takeovers is trying to convince everyone 56kb/s on 8Mbit line should be enough of "that unlimited interweb megahighway thing" for everyone and is desperately trying to shake off anyone using over 30% of their line capacity,
actually signed the infamous three strike deal with British Phonographic Industry and agreed to rat their users out to "the authorities" and terminate contracts if they find repeated offenders downloading or sharing the "nasty warez thingy stuff". As a followup of selling their soul to devil Tiscali kicked out 4 users on BPI request and then discovered that BPI actually had no intention of covering the costs of logging, intercepting, gathering and going through the evidence against all the hundreds and hundreds of silly teenagers BPI dug up on various torrents and requested Tiscalli to investigate or check and so the deal - being effectively "Tiscali pay for kicking their own clients" is currently "oh hold" until someone wants to pay for it.
So effectively, on one hand you have this elusive "loss of revenue" to megalithic industry bodies, on the other, you have ISPs actually loosing their name and users. Because let's face it - as a principle, whether you download illegal content on your line or not - who actually wants dodgy ISP that will sniff around your tail and every byte you transfer and ring alarm bells every time you download nocd crack for your games, right? It's like asking nuns to run your night club.
