Libertarian economics is free market economics, and a fundamental principle of that is property rights. Free market economies are the only economies that have lifted the poor en masse out of poverty, and such economies have large middle classes that very, very much depend on property rights.

Libertarian economics is the most radical extremist free market economics that has ever been imagined and has never been implemented and never will be implemented.

Every modern and nearly every recent historical society has been a mixed economy. The only reason the middle class exists is because it was fought for, hard, by explicitly anti-Libertarian structures (new deal style reforms and make-work projects, welfare, healthcare, unions, minimum wages, worker protections, tarrifs, GI bill, universities, very high taxes on the rich and very high corporate taxes, publicly owned infrastructure, bailouts) fighting against or protecting free markets from themselves when they inevitably crash and burn and destroy themselves and the societies around them. Without these protections free markets would annihilate the entire middle class in a heartbeat for the sake of "efficiency" as is their nature (the middle class are by definition not the owners of capital so their concerns are not considered by a capitalist economic structure), a process that is occurring albeit more slowly in the US as we speak. Markets are very powerful engines for generating efficiency, so they are good at building economic engines (through exploitation, of course) while ignoring any and all other concerns or consequences. They are a paperclip maximizer. Not entirely useless tools, but horrifyingly murderous and dangerous ones that have a tenancy to seize power with disastrous results wherever they go.

The United States, excluding the antebellum southern states, was pretty much a free market economy up until around 1914 or so.

Of course it wasn't 100%, but it was a good approximation of one. Far from destroying the middle class, it created the middle class in America. Scores of millions of impoverished immigrants arrived on the shores, and moved up into the middle class.

The income tax on the rich came later.

I've heard it claimed that the middle class was created by the New Deal, but that is not very supportable. Just look at paintings and photographs of towns and cities from the previous century. Looks like middle class to me.

If you like, take a tour of the town of Gettysburg. It's been well preserved, with quite a lot of the same structures still there from the Civil War. They look like middle class homes to me. Have a visit and tell me what you think.

It's prosperity was based on the extreme exploitation of the weakest member of its society.

Unregulated markets inevitably lead to corruption, oligarchy, and health hazards to humans.

It's more profitable to operate when there's no expense or regulation associated with negligence and malice.

https://en.wikipedia.org/wiki/Fda#History

https://en.wikipedia.org/wiki/The_Jungle#Federal_response

  The Jungle is a 1906 novel written by the American 
  journalist and novelist Upton Sinclair (1878–1968). 
  Sinclair wrote the novel to portray the harsh conditions 
  and exploited lives of immigrants in the United States in 
  Chicago and similar industrialized cities. Perhaps his 
  main goal in exposing the meat industry and working 
  conditions was to advance Socialism in the United 
  States. However, most readers were more concerned with 
  his exposure of health violations and unsanitary practices 
  in the American meatpacking industry during the early 20th 
  century, greatly contributing to a public outcry which led 
  to reforms including the Meat Inspection Act. 

  The book depicts working class poverty, the lack of social 
  supports, harsh and unpleasant living and working 
  conditions, and a hopelessness among many workers. These 
  elements are contrasted with the deeply rooted corruption 
  of people in power. A review by the writer Jack London 
  called it "the Uncle Tom's Cabin of wage slavery."

The Jungle is a novel - fiction written for the purpose of propaganda, and Upton Sinclair admitted as such. You need better sources.

Besides, selling water colored yellow and calling it "orange juice" is fraud, and is not condoned by libertarianism. Similarly, selling poison and labeling it "milk" is both force and fraud and will get you facing murder charges under any libertarian government.

The Jungle is a piece of historical fiction that was accurate while remaining fictional, was of course designed to make a point (as all meaningful writing is) and captures an era and expresses in a clear way the inevitable plight of non-wealthy people subjected to capitalism. To dismiss it in this way is to dismiss all of history itself, which is simply accurate stories about people's lives. To not read it is to plug your ears and shout "I can't hear you" about what it's like to be poor or working class under the brutal regime of unfettered free markets and the problems and horrible abuse these people face. But hey, I wouldn't want to complicate my clean and pure political ideology which is completely coincidentally directly in service of my own personal pocketbook and power with a modicum of understanding about the lives of others less fortunate, would I?

Your examples sure are clean. But the real world is dirty. What exactly is "juice?" Are you, a Libertarian, proposing that the government spend years and millions of dollars creating a U.S. official definition of "juice" for labeling purposes? What happens when inevitably companies skirt the line?

And sure if I sell you poison on purpose knowing it's poison wanting to kill you that's murder. What if I'm a company that produces milk but I cut corners and possibly some number of milk products happen to be poisonous, though I never try to poison anything? What if I build cars and realize they will explode and kill people but figure I'll make more money selling them and dealing with the deaths than a recall? What if I use my vast power and wealth to systematically suppress all knowledge about how dangerous my products are and market them as safe and "doctor-approved", watching my smoking customers die thousand after thousand? What if I sell investments I know are bad, but I lie and fake ratings for them and sell them as high-quality, defrauding people by the millions? What if I extort an entire state by manipulating its energy supply? What if I poison rivers, drinking water, give communities cancer, lie about emission test results and poison the air, create children's toys with lead all because it's more efficient? All of these examples I cited have happened, recently, in our currently non-Libertarian society, and are nearly identical to your example and nobody was charged with murder. Libertarians support fewer regulations, less oversight, more market freedom -- the freedom to do all of the above with even more impunity than they do now.

> The Jungle is a piece of historical fiction that was accurate while remaining fictional

If a historian says that The Jungle is factual, then he should be able to cite facts and would not need to cite a novel. It's really poor scholarship to cite a novel as a factual source. There's no way to tell what parts of it are factual and what are "artistic license". The book has neither footnotes nor references.

I own probably close to a thousand history books, and no, history books are not written as novels. They do tend to tell a story, and they sometimes have an agenda, but they all have footnotes and references where there facts came from, and they make it possible for the reader to distinguish the verifiable facts from the historian's opinion.

> Are you, a Libertarian, proposing that the government spend years and millions of dollars creating a U.S. official definition of "juice" for labeling purposes?

The government does now. I don't see a problem with it, nor anything unlibertarian about it.

> What happens when inevitably companies skirt the line?

They get charged with fraud.

> What if I'm a company that produces milk but I cut corners and possibly some number of milk products happen to be poisonous, though I never try to poison anything?

That's called negligent homicide. There's nothing libertarian about condoning negligent homicide. No libertarian suggests that nobody will commit crimes under a free market.

And so on for your other examples.

> the freedom to do all of the above with even more impunity than they do now.

I'm afraid you've been misinformed.

To give an example of regulations that libertarians would oppose - rent control.

If you want to impugn capitalism, may I suggest "The Robber Barons" by Josephson. Josephson seems to share your viewpoint, and he wrote an actual history book of capitalism of the period, complete with an index, sources, quotations, footnotes, all the good stuff. I have complaints with his conclusions, and I think he cherry-picked his facts to fit his viewpoint, but you'd be on much more solid ground than with Sinclair.

Just in case you were wondering, my father was an actual historian, and I inherited his book collection. I seem to have inherited his interests as well, and I constantly buy more history books. Just picked up a pretty cool one on LBJ.