Even there, from state to state, its not an absence of government interference.
True there are no tarriffs, but what really defines it is equal protection under the law thus creating and maintaining a true market driven economy.
If there were no government intervention Microsoft would have never been sued, Standard Oil wouldn't have been broken up, and the telephone company wouldn't have been chopped into pieces.
The game doesn't start and stop with a discussion on tarriffs. Free Trade in its true form is a combination of many things. In fact, there are many things that we import right now from various countries that have zero tarriffs on them at our ports. Yet its not at all a Free Trade Agreement.
But California can't impose duties on goods coming into California from States that don't have the same worker compensation laws. ie Fair Trade
If there were no government intervention Microsoft would have never been sued, Standard Oil wouldn't have been broken up, and the telephone company wouldn't have been chopped into pieces.
You're heading into different territory (which I'd gladly discuss, but in another thread). Those were also national actions. California can't put a tax on Microsoft software just because it's made in Washington, in order to encourage software development in California. California is not allowed to put up trade barriers with every State it considers 'unfair' because of different minimum wage or worker compensation rules. It also can't put up a Berlin Wall to keep businesses and people in, so both people and businesses flee as they see fit to more hospitable governments (Nevada, Florida, etc.)