Final answer:
The primary reason that national health insurance has not taken roots in America is the dominance of the private sector in the healthcare system, along with resistance from the American public.
Step-by-step explanation:
The primary reason that national health insurance has not taken roots in America is the dominance of the private sector in the healthcare system. In the United States, private firms pay and provide for most health insurance, making it different from most other high-income countries where government involvement is greater. About 80% of hospitals in the US are not-for-profit, while most physicians' offices are for-profit enterprises. Additionally, the American public plays a role in the lack of national health insurance support, as there has been resistance to government control and fear of higher taxes associated with universal healthcare.