This reminds me of the concern that Umar (ra) had when Rasoolullah was lying on the floor. Even if in Islamic point of view there is nothing wrong with driving a taxi, I think the concern of our brothers here arise from genuine love for the Ulema. It would be better if the Ulema had better income so that they can spend more time in spreading knowledge. May Allah protect our Ulema and give them barakah in every aspect of their lives. Ameen.