Sure, but AIUI they generally are not leading with a lawsuit, they're sending a cease and desist notice to your ISP, which doesn't require that kind of proof. Operators like Comcast won't require that to drop you - in fact they may give you a warning for simply downloading torrents at all, even if they are literally, actually, Linux ISOs.
You're sent a cease and desist letter with a prewritten cease and desist contract that includes confession of guilt and the obligation to pay a contractual fine, plus additional fines for future breaches.
So in reality the point of the letters is to scare you into signing and paying a fee. Actually collecting evidence is irrelevant, because the lawyer's goal isn't to go to court. That's expensive and he may lose!
The lawyers goal is primarily to stop you from pirating, and then also get lucky enough to win a small lottery payout along the way.
Send a million letters and one thousand pay? You'll be an overnight millionaire.
