If libertarianism is so great, why hasn't any country in the world tried it? The answer is that every country has tried it and every country practices it to one extent or another. This is the reason we experience progress, enjoy wealth, and have access to things like longer lives, food to eat, cities, smartphones, financial markets, useful websites, shoes, clothes, and the like. It's why we can mostly say what we want, fall in love and act on that, and do what we want in a general way provided we don't hurt others. These conditions all flow from human volition using private property (including property in ourselves) that is exercised whenever and wherever it is permitted by the authorities. Government doesn't create anything. It just takes stuff, overrides our preferences, and threatens us if we fail to comply. It has the same relationship to human liberty that a tick has to a dog. Just because ticks exist doesn't mean that dogs aren't real or are some untried experiment. Similarly, just because theft and murder exist doesn't mean that we should not rather have a world in which they did not.