Why do they take money to give job in the UAE ?

Please I wan to know why in the UAE you have to pay to get a job? some one that don't have a job they will be asking for you  to pay before you get a job, I know getting a job is not easy and lot of people are waiting for it. The job advent see or get or even know if you are going to get, to pay for it and how do they want that parson to get money to pay for a job that you have not work with or to get that money to pay for it