The modern American government, with whom capitalists are extremely chummy, has grown far too powerful domestically and has ceased to fear its people.
Corollary to the above, capitalists enjoy socialism and forms of welfare exclusive to corporations in the form of tax breaks and havens, corporate subsidies, bailouts, financial gain from underpaying employees who then qualify for welfare (the deficit of their paychecks is thus paid by the taxpayers, though 100% of their labor benefits their employer), and many more facets of this same theme.
Lobbyists, backroom deals, corruption, and pocketed politicians are factors as well, though not new ones; they've simply grown more problematic in recent decades.
The supply of workers has been flooded with hundreds of millions of women. The right to work may be appreciated by individual women, and it's certainly fantastic for capitalists and megacorporations (who are one and the same), but it's not great for individual workers, women included. Supply and demand applies to jobs and workers, too.
Outsourcing labor overseas is fantastic for capitalists and can sometimes marginally benefit overseas laborers, but it reduces the supply of jobs available to workers in the homeland, exacerbating the above.
More wealth leaves the United States than enters it; there are more sinks than faucets, and this has been the case for quite some time now.
With each passing decade, capitalists consolidate their power, extend their reach, and accumulate ever more capital (both in absolute terms and proportionally to prior metrics).
And if you do not propose one of the supposed cures proven not to work historically then you must have something else in mind. I can't conceive of it but I don't have any responsibility to since you are the one suggesting it.
On this point I'll admit that I can't conceive of the yet-to-be-conceived alternative, either—but there was a time when modern capitalism was yet to be conceived, when feudalism was yet to be conceived, and indeed, when anything but small-band tribalism was inconceivable.
In other words, known alternatives that have been tried and failed are not necessarily the only alternatives.
In any event, someone must decide how wealth is distributed—a true "free market" doesn't exist anyway, since corruption, pro-corporate governmental intervention, separate sets of rules for elites, fraternalism, corporate socialism/welfare, and other such phenomena abound. There is no level playing field, and there never has been. "Let the free market decide" is not a defense when everyone is cheating and certain persons and entities are playing by an advantaged set of rules, a set that they're rewriting to be more and more in their favor all the time.
Capitalists decide how wealth is distributed, and what they've decided (very surprisingly!) is that they keep as much as possible for themselves, and yield as little as possible to the have-nots. We've gone from CEOs earning dozens of times the salary of their average employee to CEOs earning hundreds of times the salary of their average employee, and to multibillionaire dragon hoards doubling in a decade whilst the average person struggles ever harder to afford housing, higher education, etc.
According to you, this is only fair. In my books, the only reason >90% of the population of the West aren't already living in slums and working in sweatshops is that the corporate elite have to ease the population into serfdom gradually, as they're currently doing, because they still must fear riots and revolutions if the return to medieval living conditions for the average person arrives too suddenly.