To my knowledge, it has never been tried in the history of the world, which suggests humans understand it is simply not doable.
But more to the point, how is it workable, when economies need regulations in order to protect consumers and curb greed and excesses?
This is borne out by the historical track record. If I'm not mistaken, all these successful economies like Britain, Japan, Australia, New Zealand, Germany and America, employ mixed economies, which have combinations of freedom and control, capitalism with socialism. And they are doing fantastic as far as economically and their standards of living.
Also, since these countries are doing so well and are still here, does that prove Rand was wrong when she said:
"A mixed economy is a country in the process of disintegration, a civil war of pressure-groups looting and devouring one another."
This question contradicts itself in its first two sentences:
[Laissez-faire capitalism] has never been tried in the history of the world.... [But] economies need regulations in order to protect consumers and curb greed and excesses....
The questioner can't have it both ways. Either laissez-faire capitalism exists and has problems, or it doesn't exist in the world and the world's problems therefore cannot be blamed on laissez-faire capitalism.
Observe that Ayn Rand did not title her well known book as Capitalism: The Untried Ideal. She titled it, Capitalism: The Unknown Ideal -- with emphasis on "unknown." The world has never really known what laissez-faire capitalism actually is, all the way down to its fundamental base in the morality of individualism and the efficacy of reason. America in the latter 1800s came very close to a system of laissez-faire capitalism, but not quite fully -- and certainly not in explicit philosophical understanding of capitalism's moral meaning and moral foundation.
It is mixed economies (and dictatorships) that need regulations to protect ordinary citizens -- not because laissez-faire capitalism has been tried and has failed, but because no political-economic system to date in world history has consistently comprehended and upheld individual rights, free of wrenching conflicts with anti-life, anti-rational, anti-individualist moral presuppositions.
The question is very mistaken about the "historical track record" of mixed economies. They certainly are not "doing fantastic ... economically and [in] their standards of living." Mixed economies worldwide (including the U.S.) are exactly as Ayn Rand described: they are "in the process of disintegration, a civil war of pressure-groups looting and devouring one another." (This quote can be found in the topic of "Mixed Economy" in The Ayn Rand Lexicon,excerpted from CUI p. 185.) One can readily find abundant references in the literature of Objectivism for the full story of capitalism versus mixed economies -- works such as Capitalism: The Unknown Ideal (CUI), Free Market Revolution by Yaron Brook and Don Watkins, and so on. There are also numerous summarizing excerpts in The Ayn Rand Lexicon under the topics of "Capitalism," "Mixed Economy," and related topics. Also be sure to check out the numerous references listed at the end of CUI.
If the question is attempting to assert that a mixed economy is demonstrably a system of harmful "greed and excesses," and that laissez-faire capitalism would be no different, Objectivism challenges that assertion. A mixed economy allows violations of individual rights by government, and also fails to protect individuals fully from violations of their individual rights by others. Laissez-faire capitalism allows neither. Laissez-faire capitalism consistently upholds everyone's individual rights, both by strictly limiting the prerogatives of government, and by protecting individuals from violations of their individual rights by other individuals or enterprises. Under laissez-faire capitalism, irrational "greed and excesses" are penalized by the mechanism of a free market insofar as they do not involve violations of anyone's individual rights, and punished by government when "excesses" mean initiation of direct or indirect physical force against others. Again, no one can claim that laissez-faire capitalism has been tried and has failed; it hasn't. What failed wasn't laissez-faire, and its closest approach so far in history (in the 1800s) was spectacularly successful compared to all known alternatives and subsequent interventions.
If the question is attempting to use "greed and excesses" as an indirect "code word" expression for "inequality," Objectivism challenges the premise that egalitarianism is a moral ideal. Objectivism recognizes that there is a "pyramid" of productive ability in laissez-faire capitalism, and that it is blatantly unfair to greater producers to shackle them for the alleged benefit of anyone who is less productive. Objectivism points out that laissez-faire capitalism actually does vastly more to raise everyone's standard of living than any other system ever devised by man, but capitalism does it by embodying and rewarding the morality of individualism and rejecting the morality of altruism, which committed altruists, blinded by their altruism, will never endorse no matter how much material prosperity capitalism brings.
Laissez-faire capitalism is neither utopian (in the conventional, "something for nothing" meaning) nor a fantasy (insofar man's life, both individually and in a society, depends on upholding individual rights consistently). Laissez-faire capitalism is simply the fully consistent expression and result of upholding man's individual rights (which do not include the freedom to defraud others, or to commit unilateral breaches of contracts, or to commit slander or libel against others, or to violate anyone's individual rights in any other respect).
Update: Sanction of the Victim
In the original question and again in the comments, the questioner has very forcefully stated his basic contention, notwithstanding any references in the literature of Objectivism to the actual history and economic theory of laissez-faire capitalism.
...the essential point of what I'm saying on Laissez Faire capitalism [is:] You need external oversight or regulations from the government or some such institution to have checks and balances(regulations) on the economy so consumers and workers don't get exploited and to reign in capitalist excess or greed.
Appeals to individual rights, including the rights of producers, have no apparent effect on the questioner's thesis, which proposes to infringe the individual rights of producers in order to sacrifice the producers for the alleged benefit of others. By what moral right does anyone propose to initiate physical force against producers (or anyone else)? Objectivism classifies the initiation of physical force against others as morally evil, deserving of decisive retaliatory physical force in response.
The person who motivated me to ask this question ... cites actions like your boss could make you work as many hours as he wanted without overtime; Also I think there were low wages. He called the almost completely unregulated capitalism of the industrial revolution, horrendous, and that is why we don't do unregulated capitalism anymore.
The unmistakable thrust of this formulation is that producers are going to be shackled for the benefit of others no matter what, without regard for any differences in either history or economics between full laissez-faire capitalism and nineteenth century mixed-economy capitalism, without regard for the difference between economic power and political power (refer to that topic in The Ayn Rand Lexicon), without regard for individual rights, or individualism versus altruism, or even the efficacy of reason itself (particularly on the part of the producers).
It might be asked: how can one deal with such a person, especially if he and others like him resort to all-out war on producers in order to enforce their will? Ayn Rand magnificently concretized her answer in her seminal novel, Atlas Shrugged. The fundamental theme of that work is the role of the mind in man's existence. She concretizes what makes the survival of the whole society possible, what sustains the looters, and what the producers can do about the looters. She concretizes the principle of "the sanction of the victim." A memorable explanation by Galt in Part III Chapter I puts it this way:
We've heard it shouted that the industrialist is a parasite, that his workers support him, create his wealth, make his luxury possible—and what would happen to him if they walked out? Very well. I propose to show to the world who depends on whom, who supports whom, who is the source of wealth, who makes whose livelihood possible and what happens to whom when who walks out.
What the producers need to do is stop giving their moral sanction to their destroyers. They need to learn to "shrug," to resist and oppose mysticism-altruism-collectivism-statism wherever and whenever they encounter is, and uphold reason-egoism-individualism-capitalism instead, so long as they remain free enough to speak out about it. (For further explanation of the "Sanction of the Victim," refer to that topic in The Ayn Rand Lexicon.)