But as you say the isp will still see from the amount of data you are downloading somethings up.
Already the law makers are putting the emphasis on the isps as like you say they know the tehnology. So if they allow it, well lets just say their shareholders will not be happy with massive fines and the right to operate being taken away.
This is also the reason why you should keep any wireless network secure, if someone gains access and downloads or uploads content which is ilegal for whatever reason you will be responsible unless you can prove otherwise.