It would be more difficult to remove a qaid who had a diploma. Unreliable and corrupt qaids were certainly removed from time to time but they were always hard to control because they knew their areas far better than officers of the Affaires Indigènes did, and easily dominated the jemaas.
Source: wiktionary
For that, they had a much more convincing and powerful interlocutor, one of the four qaids himself.
The man who offered to lead the Normans into Sicily was Ibn Timnah, the Qaid of Syracuse.
Source: wiktionary
According to Hermassi, all the qaids were appointed by the bey, whereas De Montety describes some of them as tribal notables whose position was ratified by the center.
Source: wiktionary