Why was Sai Baba upset with Madhavrao for demanding fifteen rupees Dakshina from a visitor?

This question misinterprets the events described in the source material. Sai Baba was not upset with Madhavrao (Shama), and Madhavrao did not demand Dakshina from anyone. In fact, the situation was the reverse. As recounted in Chapter 18, Sai Baba himself sent a messenger to Madhavrao with the specific instruction: 'Take fifteen rupees as Dakshina from Shama.' It was Baba who was requesting the Dakshina. Madhavrao was extremely surprised by this unusual request and, instead of giving the money, playfully replied to offer 'namaskar' as his Dakshina. The entire event is described as the 'play of this God,' not an incident of anyone being upset.