All this yak about the FAA causing a problem is misguided. A Federal Judge heard a case challenging an FAA ruling to shut down a warbird carrier who gave rides under the guise of instruction. Who pushed them to challenge that limited ruling? I’ve read it was AOPA but I don’t know for sure. Regardless, the case ends up in front of a judge who wrote an opinion that flight instructors are providing a professional service for compensation, the roots of commerce, and that by being present in the aircraft they’re carrying passengers. The ruling that I read sounds credible, and by the reaction of the FAA I believe they agree the ruling will likely withstand any challenge.
Moving on, how it applies to my experimental Cub is this. CFR91.319 (a) defines limitations on commercial ops.