When products are marketed as 'BPA-free', this designation refers to whether the hardener component contains BPA - not the resin. Reacted epoxy resin is considered BPA-free as long as there's no free BPA. Free BPA means the product does not contain the chemical BPA, which is used as an accelerator to help the amine hardeners cure the resin.
For example, as shown below in the TotalBoat MakerPoxy Resin SDS Section 3 - Bisphenol A content is 80 to 100%. Now, look at the CAS NUMBER, which is 25068-38-6.
Competing products touted as BPA-free and containing no VOCs, often reference the same CAS number in their resin SDS. They often call the chemical “DGEBA-Epoxy Resin”, where DGEBA is shorthand for DIGLYCIDYL ETHER RESIN BISPHENOL A (!). Others use the same CAS #, and refer to the chemical name as "Propane, 2,2-bis[p-(2,3-epoxypropoxy)
So, it’s really just a matter of semantics.