Also, if ISPs COULD charge only people who use filesharing then they'd still have to have some way of working out which people are sharing legit files, shareware, stuff they made, freeware etc. and which people are sharing copywrite material. The way mentioned just hits everyone the same.
I don't think anything particular needs to be done actually. Why? Because the ADSL ISPs are on their way to solving this already. The way I see it, it is only a matter of time before ADSL ISPs begin to charge per MegaByte instead of per month. This seems completely fair because the contention ratio effects everyone and people creating more traffic by filesharing etc. use more of the ISP's bandwidth than others in the area who only check email and play games.
So when charging per Megabyte sets in, filesharing will slump like crazy. Those that do not fileshare will probably save money. So it's a win all round, except for the filesharers
