Here's a horrifying fun fact about occupational licensing: "States consider an average of 33 days of training and two exams enough preparation for EMTs, but demand 10 times the training—372 days, on average—for cosmetologists."

Occupational practitioners, often through professional associations, use the power of concentrated interests to lobby state legislators for protection from competition though licensing laws.

Aspects of IJ's report will make your jaw drop. See, for instance, its ranking of occupations in order of most-to-least onerous licensing requirements:

http://ij.org/ol/report.php?table=3
...
Occupational practitioners, often through professional associations, use the power of concentrated interests to lobby state legislators for protection from competition though licensing laws. Such anti-competitive motives are typically masked by appeals to protecting public health and safety, no matter how facially absurd. For example, the 2011 legislative session in North Carolina saw efforts to license music therapists. The enabling legislation’s introduction stated: “The North Carolina Music Therapy Practice Act is established to safeguard the public health, safety, and welfare…”22

Similarly, the American Society of Interior Designers has waged a 30-year campaign in state legislatures seeking greater regulation of its industry, including occupational licensure.23 The cornerstone of its argument is the alleged threat to public health and safety from unlicensed interior design, yet time and again industry lobbyists have failed to produce actual evidence of consumer harm. State agencies have similarly been unable to document a need for licensing interior designers, and such claims of harm have also failed independent scrutiny.

Once practitioners enjoy the benefits of a sheltered occupation, they seldom let it go without a fight. It took multiple years and two separate lawsuits to force legislators in Louisiana, the only state to license florists, to merely reduce the licensure requirements. In the process, representatives from the florist industry fought hard against any changes to the law. The head of the state florist association argued that the licensure regime protected consumers by upholding high professional standards. The head of the state horticulture commission agreed: “If they [aspiring florists] can’t take the instruction and pass the exam, how can they do an arrangement that you and I want to buy?”25

Such arguments fly in the face of common sense—how do consumers manage in the other 49 states and D.C.?—