This system eventually broke down as the Janissaries, who had guns, lobbied to be allowed to have families. But until that happened, the Ottoman system of using a mix of slave administrators and eunuchs to run everything worked incredibly well. To return to the relationship between the Ottomans and the Venetians, after the Ottomans captured Egypt, they pretty much controlled the flow of trade through the Mediterranean. But the Venetians had centuries of experience as mariners, and also lots of boats. Speaking of ships, I ship these guys. So the Ottomans were content to let the Venetians do all the actual, like, trading and carrying of goods, and they just made their money from taxes. And that worked because both Venice and the Ottomans added value to each other.