>Taxing emissions just allows some government a-hole to make a buck and you still get the emissions how is that better?

Those emissions only happen because of the local price advantage of the externality. Globally there is no price advantage because for every winner (the person emitting the CO2) there is a loser (everyone else being harmed from the CO2). This is a clear case of individual decision making requiring an extension of responsibility. The carbon tax makes the decision maker responsible for the financial damages caused by the CO2 and thus allows local decision making to reach a global optimum.

Advocates of the free market should want local decision making to always result in a global optimum, because that is literally their position. If they want to argue that local decision making should not have to lead to a global optimum then they ruin their own position because what they really want is the right to harm others for private benefit.