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.