And while there are plastic canisters and funnels, etc. that can conduct electricity I've never seen references or guidance for their use.
The guidance is to assure that the plastic of the canister is in contact with the airplane fuel filler before pouring, and assuring that it remains in contact the whole time while fuel is being poured. We simply want to prevent an open circuit, which can allow a voltage (static potential) difference between them. Fuel flowing from a plastic canister is going pretty slowly, and not at all under pressure, so it has limited potential to create much static electricity, but good fueling discipline is still a good idea. Technically, if pouring from a plastic fuel canister into the wing of the airplane, bonding the airplane to the ground is of reduced importance, but still a good idea if you can. The point is to eliminate an initial static charge difference between the fuel source and airplane, and then prevent any build up of static which could result from fast moving particles in the fuel as it moves.