It’s easiest to see how free-rider problems apply to non-excludable, rivalrous goods, a situation better known as the tragedy of the commons. If a public park is free to access, people will use it without paying for maintenance and upkeep. As more people flock to the park, its quality is diminished. The trash cans will overflow, the crowds get packed, the grass ground down to mud. To address this problem, we typically pay for public parks with our taxes; some national parks also charge an entrance fee.
