A large portion - not all , but many. But the thing to remember is that back when Taft-Hartley was passed that was not the case. Memories of the Great Depression, a live and vibrant communist party, and a strong non-communist labor movement as well resulted in an extremely class concious U.S. working class and poor. Of course this was weakened by strong racism and misogny, but from what I understand (at a great distance) Australia is not free of either. Don't underestimate the role bad laws can play in weakening the labor movement. Restricting the conditions of "legitamate" organizing, making the conditions under which labor actions are legal, expands greatly the circumstances under which scab labor, outright fraud, and direct violence may be used to fight labor. At the time Taft-Hartly was passed the new merged AFL-CIO threatened a real general strike in protest, but did not carry it out - limiting itself to limited time strikes, and demonstrations. Mind you a general strike at that time would have been a huge risk. If it succeeded it could have forced repeal, but if it had failed, the labor movement in the U.S. would have been broken immediately instead of dying slowly. I suspect, though, that if the merger had not taken place the more militant CIO would have tried it.
A bit more history in turn. The CIO agreed to merge with the AFL more or less on the AFL's terms (in effect the more militant unions committed suicide in the name of labor unity) on orders from the Communist party. The communist party in turn was acting more or less against it's own better judgement in the face of orders/pressure from the International communist party - i.e. the Soviet Union. I often think that the AFL-CIO merger (at least in the particular form it took) was the single worst result of whole undemocratic structure and subservience to the the Soviet Union by the Communist Party USA. The labor movement made all sorts of threats as Taft-Hartly moved through Congress which were ignored because Congress knew the merger had defanged the labor movement. I can't help but wonder if it would have passed in the absence of that merger.
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