Is it wrong to cut a homeless man’s hair without a license?

Mr. Montes de Oca was studying cosmetology but hadn’t yet received a state-issued license. So the Arizona State Board of Cosmetology opened an investigation. Its executive director pronounced Mr. Montes de Oca’s charity work a “real risk”—never mind that parents routinely cut their children’s hair. Then Gov. Doug Ducey stepped in, ordering the board to end its investigation and waive any penalties against Mr. Montes de Oca. The governor has since ordered a review of state-licensing board requirements to make sure they serve the public interest.

On Wednesday, more than a year after Mr. Ducey’s intervention, the Republic, the state’s largest newspaper, published the results of its investigation of Mr. Montes de Oca. The paper reported that the board had received an anonymous complaint accusing Mr. Montes de Oca of offering to accept drugs in exchange for haircuts. “Word of the drug claim was sent to Ducey’s office just before the board was scheduled to drop the issue,” the Republic reported. Mr. Montes de Oca said the allegation was false and “ridiculous.”

The article also mentioned Mr. Montes de Oca’s rough upbringing and his 2010 arrest, conviction and imprisonment for domestic violence. Mr. Ducey called the article a “smear campaign” and tweeted: “I’ve said I believe in second chances. And guess what? I ACTUALLY do.”

Yet Texas insisted she obtain a cosmetology license, which would have required 750 hours of irrelevant barber training. Even after retaining the Institute for Justice, a public-interest law firm, to challenge the requirement, it took Ms. Brantley nearly two decades before she was fully vindicated and Texas reformed its laws in 2015.

In the 1980s, the District of Columbia government shut down Ego Brown’s shoe-shining business, citing a 1905 ordinance forbidding shoeshine stands in public spaces. Mr. Brown employed homeless people, providing them not only with a job but a shower and a tuxedo uniform. Then-Mayor Marion Barry ignored repeated requests to reform the district’s shoeshine ordinance. That law was eventually struck down in court, but the situation has hardly changed, as street shoe-shiners must still obtain numerous permits, submit to a background check and pay more than $1,500 in fees.

Sandy Meadows worked as a supermarket florist in Louisiana, the only state that licenses flower arranging. When the Louisiana Horticulture Commission got wind that she lacked a license, it threatened to close the store, which dismissed her because it had no other work for her to do. Although the store had been happy with her work, she was unable to pass the licensing exam, which included a written component and a test in which state-licensed florists judged their potential competitors’ arrangements. The pass rate was well below 50%, and florists who had been practicing without problems in other states for years often failed. Meadows, who had no other vocational skill, died destitute. Louisiana is now considering a repeal of the license requirement.

Of late licensing laws have begun incorporating dubious education requirements. The District of Columbia is in the process of requiring day-care workers to possess an associate’s degree, and Tennessee recently passed a law making a high-school diploma a prerequisite for a barber’s license. Education requirements can be a Catch-22: In 19 states, occupational licensing boards can suspend licenses for falling behind on student-loan payments—making it impossible to earn money and catch up on the payments.

Licensing requirements aren’t the only local laws that harm the poor and struggling. In 2012 then-Mayor Michael Bloomberg banned food donations to New York City’s homeless shelters on the ground that the food might be salty, fatty or otherwise unhealthy. In 2013, Louisiana health officials ordered the destruction of 1,600 pounds of deer meat donated by hunters to a local shelter, though it was processed at a state-certified slaughterhouse.

Policy makers looking to highlight the deleterious effects of regulations often focus on entrepreneurs. But the unintended consequences often fall most heavily on the disadvantaged. The government is supposed to provide needy citizens with a safety net, not ensnare them in a web of red tape.