That's putting too much faith in the so called free market, a term used by business to keep government regulators an arms length distance away from its practices. Business has gone out of its way to finance political parties and politicians to ensure that distance remains, and the US economy is filled with self regulating companies with almost no oversight. In the US, business is the core of society, protected on one hand by a strong military and weak government, and fed on the other hand by a large population eager to consume. One may wonder why we have any elections at all when business is king.Unions were only effective in countering the "externalities" sometimes posed by laissez-faire free market capitalism such as exploitation of child labour, destruction of workers' welfare in the quest for minimizing cost but once these externalities are resolved or mitigated to a satisfactory level, the usefulness of unions are really limited. And not only that, unions are now becoming a barrier of trade almost hindering the working of the market economy and suppression of quality and innovation for mediocrity. But this is not limited to just unions, any measures such as government regulations, environmental measures and etc. adopted to counter any externalities not being able to be resolved or resolved effectively by the mechanisms of the market economy all have the same limitation as unions; their effectiveness is only limited to the point of resolving and mitigating the externalities not resolvable by the mechanism of the market economy. Beyond that, they become a hindrance.
I generally prefer the European models, where The People elect government and hold it accountable for carrying the goals and aspirations of a society all wrapped up in ethics and morals rooted or not in religion. Business plays an important role but always within government parameters that are often precise, both in scope and operational roll out.
This isn't to say that the European model is perfect, far from it, and I could write a litany of complaints about its excessive regulatory framework, the outsize influence of unions, or endemic unemployment. I believe the US could benefit from elements of the European model and Europe from the US model.