Why does the government need to provide public goods?

The government needs to provide public goods because these goods are non-excludable and non-rivalrous, meaning that individuals cannot be effectively excluded from their use, and one person's use does not diminish the availability for others. This leads to market failure, where private markets may underprovide or not provide these goods at all, such as national defense, public parks, and street lighting. By providing public goods, the government ensures equitable access and promotes overall societal welfare. Additionally, government provision can help stimulate economic activity and address externalities associated with public goods.