There was no money, because neither the California Indians nor the Franciscans had a money economy: they had a customary exchange-based economy.
The Spanish military wanted the Indians to get into a money economy, because he wanted them to pimp their own sisters, wives and daughters to the soldiers for money and liquor. When Serra opposed this, they agitated to the governor to get the system taken away from the Franciscans.
Eventually the Indians ended up like serfs on the haciendas, and sexual consorts for the soldiers, but this was not Serra's doing. He strove, labored and suffered to obtain the well-being and redemption of the California Indians all his life.
In this tumultuous contact of two civilizations (Spanish and Indian) the Spanish ascendancy was inevitable; but the way they did it was unconscionable. Serra was an opponent of the colonial military power structure and did everything he knew how could to protect the Indians and to safeguard their human dignity.
If we were in the exact same situation, with the same range of options, we would have done nobly indeed to do the exact same thing.
Thanks