You are missing that fact that the govt is made up of idiots. That's the usual explanation for things of this nature.I do have to laugh a bit at those charcoal canisters on bikes. Their purpose is to capture evaporative emissions while the tank is being filled with gas, yet I've yet to find a motorcycle gas tank that can accomodate the filler neck from a gas pump. It's usually necessary to hold the California emissions "bellows" device up with one hand to switch the pump on... thus leaving a gap between the pump and the tank and negating the benefit of the evaporative controls system. Am I missing something here?
Even if the bellows device matches the cap hole the nozzle has to be pushed so far into the tank for gas to pump that you can't fill the tank even half full. So you got to hold the bellows with your hand thus rendering the charcoal canister useless.
But I wouldn't tell CARB any of this. They would mandate foot long fuel inlet extensions on the fuel tanks.