“[Trade licensing] almost inevitably becomes a tool in the hands of a special producer group to maintain a monopoly position at the expense of the rest of the public. There is no way to avoid this result.”

All licensing by government is by definition, unlawful. As to one of the results of "trade licensing", the statement is right on accurate.

Thus we have the private American Bar Association monopolizing the 'justice' system, the American Medical Association monopolizing health care, and the myriad of unions that monopolize construction, manufacturing, transportation, communications, and public services. Just a bunch of mobsters hijacking private enterprise -- racketeering pure and simple.