There was a post a few months ago about a guy who really liked hair styles. He was about to become a barber but had a conversation with a successful entrepreneur that made him realize that being a barber doesn't scale. He went on to build a hugely successful franchise.
There's a difference between the business and the job. Being a Barber doesn't scale in the same way a search engine or car manufacturer with 1 employee doesn't scale. There's no reason a company based on haircuts can't scale though by hiring more employees, and without knowing where you live I'm sure some hairdressing chains exist.
If you mean that scales exponentially, so the employee-value graph isn't linear, I guess that'd be different and you're probably right.
[1] http://en.wikipedia.org/wiki/Supercuts