Not all of them are hired by the company seeking someone. Some work for placement agencies where you go to them and have them seek jobs. I think others work on their own and freelance. There are websites where you can enter a field and get people's names, so it wouldn't be hard to scan the job postings and then call people up. My mom had been working with placement agencies to find her job and told me to ask who was paying the fee if I got hired.