[Econ] Hi, here is a question about ”externalities ”!!

Externalities occur when one person's actions affect another person's well-being and the relevant costs and benefits are not reflected in market prices.A negative externality arises when one person's actions harm another. When polluting, factory owners may not consider the costs that pollution imposes on others. However, they must continue to run the business in order to produce the goods necessarily to the public.Therefore, government intervention is necessary by imposing laws or by setting legislatives on the factory owners so that they must be paid higher water and sewage charges. Lighthouses are one of the most famous examples that economists give of public goods that cannot be privately provided. Economists have argued that if private lighthouse owners attempted to charge ship-owners for lighthouse services, a free-rider problem would result.Lighthouse owners realized that they could not charge shipowners for their services. Therefore, externalities are unintended consequences due to free rider problem and government involvement is necessary to provide lighthouse (public good) in order to reduce casualties in the sea.