A License For Protection: Why are States Regulating More and More Occupations?
The recent boom in occupational licensing has been driven in part by people who are already members of that occupation, out of a desire to increase their wages by limiting entry into the field, argues this analysis of the history and value of occupational licensing. State governments are generally supportive, says the author, because the revenue generated by licensing fees and education can be used to offset the costs of monitoring and balance state budgets.
Kleiner, M. (2006). A License For Protection: Why are States Regulating More and More Occupations? CATO Institute. https://www.cato.org/sites/cato.org/files/serials/files/regulation/2006/10/v29n3-2.pdf