Up until the late 1800's, barbering was predominantly an African-American profession (for America), especially in the south where nearly all barbers were black.
Before the Civil War (1860s), these were mostly slaves. As such, barbering was looked at as a lowly service occupation, and lowly service occupations were mainly filled by members of the lowest classes, slaves being the lowest.
However, after emancipation, black barbers were well positioned to take advantage of their finely honed skills and the relationships they had established within the white community. Barbers were among the first ranks of black citizens to accumulate some degree of wealth, and they used their social and material capital to uplift their own people. The first black-owned insurance companies were founded by barbers, and insurance is ultimately about amassing financial capital that’s used to invest in other financial instruments, providing a solid foundation for newly-liberated black communities to flourish.
Meanwhile, an unprecedented wave of immigration was migrating into the north, with massive amounts of folks from Italy and Ireland especially showing up in New York and spreading out westward across the country. Among these immigrants was a large number of barbers, and while they were able to establish shops that catered to their own immigrant communities, they were highly frustrated by their inability to expand into areas served by black barbers.
So it was around this time they started lobbying states to establish licensing boards to promote barbering as a respectable skilled profession and ostensibly to fend off disease and infection, which, as noted in the beginning, was a pretty thin pretense. They pretty much engineered the rules to target black barbershops, including the requirement for barbers to attend formal barbering schools. So essentially, it became no school, no license, and the first schools were by design, not open to African-Americans. This was very effective in almost destroying the black barber professional.
Within a generation, the industry was totally flipped on its head as black barbers were forced out of white areas. Barbering went from being predominantly black to completely segregated, except in pockets of the south where the old ways were held tightly. But by the nineteen-fifties, black shops served black men and white shops served white men, and the remnants of this segregation are still evident even today (Hair Studio vs Barbershop).
So was the barber license simply a legal weapon devised to drive blacks out of the barber profession? Well, there is no hard conclusive evidence or documents that state definitively what the motivations were, but the timeline and the damaging effects make it pretty evident. In a most charitable assessment, I’d say it could have been immigrants wanting to simply establish themselves and organize into something like the trade unions and guilds they belonged to back in Europe, and it had the unintentional (but surely welcomed) effect of driving out black barbers and creating more opportunities for white barbers.
If this sounds too conspiratorial, I’d encourage you to look at the massive and concerted efforts to cut off African-American success in the Reconstruction, post-Reconstruction, and Jim Crow eras. The disenfranchisement of the African-American barber is really among the least of the oppressions African-Americans were faced with at that time.
Lastly, I’ll note that the pendulum is starting to swing the other way. States like Arkansas and Texas have recently begun introducing legislation to do away with licensing requirements, allowing the free market to determine who cuts hair and who doesn’t. The thinking is, if you’re an unskilled barber or unclean, you simply won’t attract clients. If you’re good, you will. And the universe will be balanced again.