Final answer:
Private contractors in ancient Rome responsible for building public works and tax collection were called publicans. They were part of the equestrian class and operated by bidding for tax collection rights, recovering their investment through provincial tax revenues.
Step-by-step explanation:
In ancient Rome, private contractors who were responsible for the construction of public works and the collection of taxes were known as publicans. These individuals, part of a broader class called the equestrians, played a crucial role in the economic system of the Roman Republic. The publicans would bid for tax collecting contracts with upfront payments to the Roman government, essentially offering a loan. They would recuperate their investments by collecting taxes in the provinces, keeping any surplus over the bid amount, and a commission from the government. Publicans were also involved in executing large-scale construction projects like building aqueducts, theaters, and managing state-owned mines.