1. Corporations don't want one.
We tried to let them define themselves as people, so this isn't really surprising by now. I mean, come on, there are a tragic amount of people I know who don't even consider refugees and immigrants as people. But no, Big Oil and private security companies like G6 are definitely more human.
A free market wouldn't help them at all--it would open up possibilities to smaller businesses without as much political clout. In the age of super PACS and corporation-people, there's no way privileged companies would want to sacrifice that power. Remember, we're the country that prioritized the DAPL over Standing Rock protesters; the country where the residents of Flint, Michigan are still paying their water companies for lead-poisoned water; the country that really didn't care all that much when KKK members backed our current president. We know where our priorities are, and they're with the guys who have designer logos and lots of lawyers.
2. The term means different things to different sides of the political spectrum.
Ask a traditional conservative what they think a "free market" is, and they will likely mention laissez-faire economics or small government. Ask the average liberal and they'll have different ideas, and the same with a libertarian, anarchist, and so on.
Nobody agrees on what it means to have a "freer" economy. In the 19th century, many people would have said that the perfect economic freedom would be to let slave traders make the most money. Very free for them; not so much for the slaves. This past few years, some might define their ideal market as one with severe restrictions on funding medical marijuana research, or one with fewer restrictions on gun sales, or the ability to deny an LGBT couple a wedding cake because of your beliefs.
A free market is supposed to be defined by the consumers, but today more than ever a lot of consumers conflate the entire concept of "freedom" with the restriction of it for others. It's a paradox worthy of George Orwell--one man's liberty is what others will call special treatment. We keep getting scared that minority rights getting attention is the precursor to some sort of evil anti-American power grab.
3. Much of our economical decisions are only meant to help the middle class and above.
America's in the middle of cutting social security, welfare programs, education, and so many more support systems that were, until recently, considered the proud pillars of a free and prosperous democracy. We've come from "no taxation without representation" to "single Black mothers should only be able to buy ramen with food stamps because they don't work enough, dammit!". Although arguably minorities are always oppressed by those in power, America has taken punishing poor people to a new low as of late. And the reason for all of these cuts and defundings? To help the average Joes among us, as well as the guys who pay the average Joes. Who else is there?
In the long run, it doesn't even matter that much what the Dow Jones is or if the middle class unemployment rate goes down. Our theories and discussions of the American economy often ignore that people who are scraping by on nothing won't be affected much by broad policies. Want to help equalize financial freedom for everyone, though? Here's a radical idea: maybe try raising the minimum wage instead of slashing EPA budgets or taxing Mexican imports. Just a thought.
4. A free market at home isn't a free market abroad.
Companies are outsourcing a lot these days (although not as much as some would like you to believe), to avoid regulations and pad their wallets more. As much as we try to change policies for the whole nation, we have our fingers in pies all over the world. If we want to start talking about the American market as a whole, we need to stop pretending like we don't use other countries as back doors to our successes. If free markets are ones that allow for true competitive economics, then we have to stop letting some of us get head starts before everyone else.
5. Free market policies contradict the fear of socialism & communism we have.
Ever since Bernie Sanders tentatively broached the subject of American socialism, we've resurrected our Red Fear, even when the ideas in question are only slightly close to communistic beliefs (or not at all). Universally free healthcare is accused of being practically full-blown Marxism--and don't get us started on paid maternity leave, or unions, ick. Sharing is caring, until you get paranoid. I mean, we might still trade with socialist or communist countries like China, but business is business.
Overall, we throw around the term "free market" around promiscuously these days, but in theory and practice America is vehemently opposed to the idea. Maybe if we get around to clarifying exactly what we mean by "free"--and who we think about when we talk about "American consumers"--we might be able to put our money where our mouths are.