My guess is never. CARB has been around since 1967.
I suspect that like so many other social, environmental, and political subjects nowadays that the closer you get to 50% “consensus”, the harder it becomes to even get another 1%, until it finally becomes a stalemate and both sides claim majority status.
I actually miscounted. Thirteen states plus DC have adopted CARB standards regarding Low-Emissions Vehicles. It used to be sixteen, but AZ and NM repealed their laws.
Of those, eleven have also adopted CARB Zero-Emissions Vehicle standards.
No state adopts all of CARB’s nonsense, though we are all somehow cursed with CARB-compliant gas cans. I hate those things, and haven’t bought one in years. I buy metal “utility” cans (Jerry cans) and use them how I want.
:):)