Here is how lawyers in Germany do it. They ask ISPs for the person behind the IPs (cough, cough, carrier grade NAT) and then they send cease and desist letters demanding 800€. If you sign their letter you are considered guilty but avoid further consequences, similar to a plea bargain.
It only takes a dozen people having money and fearing court for this to be profitable. The lawyer doesn't want to go to court because that costs money, he just wants you to confess and get paid.