Uh, Dahh - Why wouldn't a person driven by tax wealth not want to tax the biggest potential commodity?
Simple math "It is the largest investment in a falling marketplace"
Also considering what they do, why wouldn't ANY broker or trader not want to get into "carbon trades"?
As carbon based life "trading carbon" is the best scam since bottling tap water.
Just think a little, regardless of what you use as a source, how you move or store it... carbon is anything we eat, burn or move.
Taxing "air" we exhale may even be $better$, ohhh wait we are trying to do ;-)