The best businesses are hungry for top talent. A good sales person, for example, can generate a lot of revenue for a company and push them past their competition. As a result, businesses will often hire special companies that specialize in executive search and selection to find them the best possible executive candidates. Companies outsource their head hunting for a number of reasons.
First, often times businesses lack the resources to devote to recruiting the best sales jobs. Thus, outsourcing to an executive search firm saves these firms time. Second, executive recruiting firms often have access to a wider talent pool, and thus these firms can often find better recruits than if businesses handled their recruitment themselves.