Here, a medley, that reads like a B side Backwards,

“A common example of a free rider problem is defense spending: not one person can be excluded from being defended by a state‘s military forces, and thus free riders may refuse or avoid paying for being defended, even though they are still as well guarded as those who contribute to the state’s efforts. Therefore, it is usual for governments to avoid relying on volunteer donations, using taxes and, in some countries, conscription instead.”

(Source: wikipedia)