How do intermediaries introduce people to work for free and how do they charge?

At present, many intermediaries (note that intermediaries are not headhunting companies) charge in two ways: one is to charge job seekers who apply for jobs, and the other is to ask the company for the fee of introducing employees. Of course, these two situations are relatively common at present, and now there is a shortage of labor, and enterprises are willing to pay a certain fee to intermediary companies. If it is labor dispatch, then they have other ways to make profits.