Can you explain why Sai Baba sent Shama to collect fifteen rupees Dakshina from Madhavrao Deshpande?

This appears to be a misunderstanding of the events described in the source material. According to the text, Sai Baba did not send Shama to collect Dakshina from Madhavrao. The instruction was the other way around: Baba sent Madhavrao to collect fifteen rupees as Dakshina *from* Shama. As detailed in Chapter 18, Madhavrao came to Shama and relayed Baba's message, stating, "'Aho, there is a message from Baba, and I have brought it: 'Take fifteen rupees as Dakshina from Shama.'" Madhavrao himself was surprised by this directive. The text clarifies that the instruction from Baba was for Madhavrao to go to Shama, not for Shama to approach Madhavrao.