If retailers do very well in airports, why aren't there more service businesses in airports, such as barbershops?

I would imagine that a disproportionate number of airline passengers are businesspeople- and (this should not be taken as sexist, racist or any kind of -ist) disproportionately men heading to business meetings.

Wouldn't a Great Clips or other quick-service barber in an airport do well for this demographic, as long as you don't have to wait for a haircut? "Drat, I have that big meeting with a new client in Seattle, but I've been working so much and have an 8am flight, so I just can't make it to the barber in time."

US passenger trains often had barbers on them until the mid-1960s, evidencing that businesspeople on trips do need this.