Final answer:
The reason prohibition is deemed a failure is due to the public's resistance to the ban, the rise of organized crime, and the challenges in enforcing such laws, which mirrors the sentiment that you cannot legislate morality.
Step-by-step explanation:
The primary reason the author believes prohibition is a failure is based on historical evidence from the Prohibition era in the United States. The difficulty in enforcing the ban on alcohol, the general public's desire to obtain alcohol, and the rise of organized crime exploiting this demand, all led to the belief that prohibiting substances is ineffective. The author suggests that trying to legislate morality and control people's choices through restrictive laws, like the large soda ban, is destined to fail due to the public's resistance and the challenges in enforcement.