Matt Yglesias dreams of a world where rogue plumbers slip silently through the night, fixing leaks and then escaping before the government can catch them and bury them in paperwork.
Any honest and humane opposition to licensing bodies must necessarily begin by targeting the traditional professions. The AMA's stranglehold on medical education vastly outweighs the effects of state licensing electricians in terms of economic, let alone public health and safety, terms.
You will always find anti-licensing allies in big business as long as you are trying to undermine trade unions, but they have no interest in any principle beyond that of broad opposition to organized labor. Licensing requirements for all sorts of occupations may be problematic in theory, but it's short-sighted to make common cause with anti-labor forces to do away with specific forms of licensing in isolation of anything else.