For example, if the community's public water supply is running low, rather than contributing to the public fund, a person may elect to put in his own pump. Unfortunately, this is not a practical solution to the VP in the general case. It is not practical for everyone to build their own roads and phone system. As we discussed earlier, investments often produce greater return when the input from many individuals are combined. Even with a heavy load of freeloaders, group effort is often more productive than individual effort.
Public television is probably a good example.
The SD seem to belong to a general class of problem that arises whenever an object is actually a composite of sub-objects which are essentially alike but very small compared to the composite. Consider the beach and the sand it is made of. Considering the fluctuations of the wind and water and other random phenomena, it is impossible to detect the removal or addition of one grain. The dilemma is that the event of one grain removed is not detectable but the accumulation of millions of grains removed is detectable. For further emphasis, consider the possibility that you owned the beach.