How job seekers in Kenya have fallen victims to scams advertising on social media

Some organizations advertise job vacancies year in year out. But surprisingly, if you visit their work places you will find someone doing that job. Why don't they advertise internally? Some people have fallen victim to scams advertising for jobs and especially on social media, and it leads to people losing money.

If an organization advertises for vacancies, it is prudent for them to announce the names of those they have recruited? Why spend money on advertisement and manpower and fail to acknowledge those recruited. Some firms do it, but only one picture of a person is placed in the newspapers. When job seekers ask for jobs they are told that adverts were placed in the print media four months back, but they don't acknowledge employing anyone.