I'm going to assume that part about lenders successfully suing tax preparers for providing client-authorized copies of tax returns is an urban legend.  What is heard in seminars, unless the course materials cite a specific case, is akin to what is heard in barber shops.  In fact, the AICPA does have a handout on the wrong way and the right way to do it:

https://www.aicpa.org/InterestAreas/FRC/DownloadableDocuments/Third_Party_Verification/QA_Third_Part...