Even worse, they are given free access (no warrant) to ISP information about the individuals they presume to be infringing so they can tie an identity to an IP linked to infringing material.

Lawyers win either way, via the fines that they ask for (people are scared that this could escalate and just pay), or the fees to fight the fines (usually a letter highlighting the situation that personal information was obtained without a court order). So they have all the incentive to propagate the practice.