What is the purpose of 3rd party reporting?
Isn't that accomplished under the nrst (even if you choose to call it something else?)
Yes it is.
Third party reporting is accomplished when both parties of a transaction are required to report. The employer reports wages withheld to the IRS and to SS; the employee reports his wages to the IRS along with documentation that includes FICA taxes withheld.
The FairTax only requires that a report be made by the tax collector.